my mac mini (M1) doesn't start all the way, and keeps rebooting

If you can get into Safe Mode, try using the Terminal command line to re-download Big Sur and re-install on top of your existing system. But before you do, try burning a 16GB+ flash drive in case you need to completely wipe out the internal disk and install from scratch.

Download Big Sur via Terminal:

softwareupdate --fetch-full-installer --full-installer-version 11.6

Format a 16GB+ USB Flash drive and name it "MyVolume"

Create a bootable Flash macOS Big Sur Installation disk

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

First just try running the installer in /Applications/Install macOS Big Sur and re-install on top of your existing system.

Make sure you have a backup of your data before you attempt this:

If this fails you will need to boot into the Recovery Mode (hold power till you get to the startup option screen and select the Recovery Mode). Then click Utilities and Startup and enable USB Boot. So you can boot from the flash drive. Then insert the Flash drive and restart while holding power button. Choose the flash drive and boot from that. Then you can erase your internal drive with Disk Utility and re-install Big Sur. Then restore your data from backup.

Building on the great suggestion from @James Brickley.

Only If the wipe and reinstall be required.

To perform this action will require booting from a Bootable Installer. This will have to be performed from a Qualifying Computer to run the version of macOS to be made on the Bootable Installer. Example : Bootable Installer of Big Sur would have to be done on a computer that Qualifies to run Big Sur.

The Below will Wipe ALL Data from the drive and no do overs - period.

Once that is done read on for preparing the Destination computer  >> Special Notation - works on Intel Based Apple Computers & May on Apple Silicon M1 CPU

Extra Special Notation regarding the Touch ID equipped Apple Computer. About Startup Security Utility and Must Enable from Recovery Mode the ability to boot from External Drive Before Attempting.

The Mac Mini M1 does not have Touch ID but does require enabling the Secure Boot aspect enable to boot from External Drives.

1 - Shutdown computer and disconnect all external drive Except the newly created Bootable Installer.

2- Restart and immediately hold the OPTION key until the Startup Manager appears and choose the USB Drive. 

3 - It will present options >> Disk Utilities >> View >> View ALL attached Drives. 

4 - Choose the Upper Most Drive ( not the volumes indented and list below ).

5 - The drive normally is called Apple Media or Apple SSD - that is the drive to Erase and format as APFS with the GUID Partition Map. 

6 - Once that is done >> backup out of Disk Utilities and choose install macOS. 

7 - Follow the prompts and it may automatically reboot several time. 

8 - Upon a final reboot - Setup Assist will present with the newer version of macOS.

Actually, both P.Phillips and myself are WRONG. I just booted an M1 into the Options and Security Startup and the option to enable USB Booting is not there like it is on T2 equipped Macs. I stand corrected! I hadn't messed with it yet on my M1.

Encryptor5000 is correct about the necessary boot requirements with the internal SSD impacting the ability to boot from external media via USB. External booting is allowed but if the internal SSD is completely broken or otherwise not working then you cannot boot at all. If the SSD is not physically damaged / malfunctioning a second working Mac with Thunderbolt data cable and Big Sur Apple Configurator will be required to revive / reset it. This will fix the internal SSD volumes on the M1 and can even reload the entire operating system via Apple Configurator.

At a very low level booting from USB on an M1 involves some interaction with the internal SSD. If the volume is corrupted, incomplete, etc. this could prevent booting from USB and again, Apple Configurator to the rescue.

Internet Recovery does not exist on the M1 Macs. This is a shame as it means some users will possibly be bricked bad enough to need Apple service at an Apple Store or 3rd party or their employers IT department. Though it should be a rather rare event. I've not run across a user who bricked their M1 to this extent yet. Only fellow engineers doing things the average user would never attempt. Although if an update / upgrade is interrupted at the worst possible moment, the Mac could potentially be bricked in this manner.

Monterey is adding an Erase All Settings and Content option which will nuke the Data volume and recreate it. This means we no longer will need to re-image Mac's that are to be recycled to new users at work. They have been wiping out the Macs and reloading everything from scratch. This will save a lot of time and it will make it easier for a consumer to reset a Mac to prepare it for resale or transition to a new user.

This is accurate for Intel-based Macs but not for M1 or future Apple silicon Macs.

With Apple silicon Macs, there is no need to permit external booting (it is already enabled). This is because each boot volume has its own security policy, whether internal or external. When a new startup volume is connected (usually external), the Mac first reboots to recoveryOS and gets existing admin credentials in order to create a new security policy for that startup disk. More details can be found here (see the note at the end of the article): Startup Disk security policy control for a Mac with Apple silicon - Apple Support

With bootable installers in particular (as far as I'm aware), M1 Macs do not actually start up from the bootable installer; they only leverage the macOS installer stored on there. Everything else is accomplished directly from the internal recoveryOS.

Also, it is not possible to fully erase the internal drive using recoveryOS. This is due to the following:

• The default drive configuration for an M1 Mac contains three APFS Containers:
  • Apple_APFS_iSC (disk0s1 / disk1, iBoot System Container): This APFS container is special and cannot be recreated outside of a DFU restore. It contains various firmware components and boot materials, including the LocalPolicy files.
  • Apple_APFS (disk0s2 / disk3): This container contains a typical macOS installation, and can be freely erased.
  • Apple_APFS_Recovery (disk0s3 / disk2): This container is special and cannot be recreated outside of a DFU restore. It contains System Recovery, a dedicated copy of macOS Recovery that exists even if disk0s2 gets erased. Removing this copy of macOS Recovery renders the Mac unbootable, requiring a DFU restore.

• macOS Recovery will not permit you to delete or erase disk0s1 or disk0s3 for safety reasons, rooted in the above descriptions. As a result, it will prevent any attempt to erase the top level of the internal drive. (Also, disk0s1 and disk0s3 are hidden from Disk Utility.)

To safely erase an M1 Mac:

The truly failsafe method

Restore the firmware. This is also the only true way to erase the entire internal drive. (The IPSW restore image will recreate the two special containers.)

The reasonable and failsafe method

1. Shut down your M1 Mac.
2. Press and hold the power button (or Touch ID) until Startup Options begins to load. This boots macOS Recovery.
3. Select Options and click Continue. This continues into the recoveryOS.
4. If you're prompted for an administrator password, skip to step 7.
5. The utilities window should appear. At the top of the screen, select Utilities -> Terminal.
6. Type "resetpassword" without the quotes and hit Enter (Return).
7. The Recovery Assistant should launch. At the top of the screen, select Recovery Assistant -> Erase Mac.
8. Follow the onscreen prompts to safely erase your Mac. (This preserves the two special containers.)
9. Connect to the Internet to activate your Mac when prompted.
10. When activation is successful, you should see the utilities window again. Select Install macOS and click Continue.
11. Follow the onscreen instructions to install macOS.

If you want to use a bootable installer for installing macOS, skip steps 10-11, attach the bootable installer, complete steps 1-2 again, but select the bootable installer when prompted.

The Disk Utility method (not really recommended unless you don't want to erase everything)

1. Shut down your M1 Mac.
2. Press and hold the power button (or Touch ID) until Startup Options begins to load. This boots macOS Recovery.
3. Select Options and click Continue. This continues into the recoveryOS.
4. If you're prompted for an administrator password, enter it to continue.
5. The utilities window should appear. Select Disk Utility and click Continue.
6. Click the View button, then select Show All Devices.
7. Choose the volume, container, or partition that you want to erase. In most cases, there is a single APFS container on the internal drive, housing one or more volumes. In this case, select that APFS container.
8. Click Erase. Choose these options, then click Erase Volume Group. If that option isn't available, click Erase:
   1. Name: Macintosh HD
   2. Format: APFS
9. You might be warned that you're about to erase your Mac. Confirm the prompt. Your Mac should then restart.
10. Connect to the Internet to activate your Mac when prompted.
11. When activation is successful, you should see the utilities window again. Select Install macOS and click Continue.
12. Follow the onscreen instructions to install macOS.

Again, if you want to use a bootable installer for installing macOS, skip steps 11-12, attach the bootable installer, complete steps 1-2 again, but select the bootable installer when prompted.

Correct, you still have to enable booting from USB. However, the rest of the information from @Encryptor5000 is correct. It may require reviving / resetting via Apple Configurator and a second Mac with Thunderbolt data cable as you cannot boot an external volume without the internal volumes at least partially working. If an internal SSD failed, you would not able to boot with an external volume.

Ouch... Yes, I would have recommended the Apple Configurator and a DFU Revive / Recovery if all else failed. Good thing you had an extra Mac and a proper USB Thunderbolt data cable which is required.

It is a shame that Apple did not implement Internet Recovery for the M1 Mac's. It would be very useful to boot a RAM drive off the Internet to clean install an M1 Mac. The DFU method is much like recovering a bricked iPhone / iPad. Target Disk mode has been changed to Shared Drive and varies a bit in the way it works. I guess the amount of work involved in reimplementing Internet Recovery was considerable so they skipped the feature (for now). Anyone without a second Mac to use with Apple Configurator would need to potentially take their device to an Apple Store or service center if they managed to brick it to the point where DFU recovery was required.

Please can you add me up to your developer team I find it hard accessing anything towards the developer program I will truly be glad please 🙏🙏 email

please anyone 🙏

[Personal Information Edited by Moderator]

An Apple Developer account is free. You only pay for the ability to sign executables and distribute software via the App Stores and access to developer beta releases that occur prior to public beta releases. As well as developer support from Apple. https://developer.apple.com

The cost for a developer account is $99/yr and is a reasonable amount if you need the paid features. Otherwise you can do quite a bit without paying.

It is certainly cheaper than most other developer licensing from Microsoft or JetBrains, etc.

Thank you for the clarifications - and thanks also to James for confirming that. I'm guessing something may have changed since macOS Big Sur 11.1 when I did some testing.

On a Mac with the T2 Security Chip, external boot can be enabled (as far as I remember) by booting into macOS Recovery, selecting Utilities -> Startup Security Utility, authenticating when prompted, and then selecting "Allow booting from external or removable media".

How would one enable external boot for an M1 Mac? From what I remember, Startup Security Utility does not present an option to permit or restrict external booting on M1 Macs.

Also, do M1 Macs still respond to the Option key being held down? I thought the only way to access the boot picker was to shut down the Mac, and then press and hold the power button until Startup Options loads.

Interesting and thank you :-))

Will revise if posting additional info. for such a situation for M1 CPUs

Yes you hold the Power button to reach the Startup Options screen. Options is like Recovery Mode. All the old hotkeys no longer work.

Mea Culpa and major mis-informed I am.

Apologies the the ASC Team.

Note: big error my part - did all Testing on MBA M1 with Bootable Installer and not on M1 Mac mini

User wrote " This is accurate for Intel-based Macs but not for M1 or future Apple silicon Macs. "

Respectfully disagree with the Assertion of not requiring the " Enable to Boot from External Drive " from Recovery Mode first.

Have created, on an M1 Mac Mini, a Bootable Installer of Big Sur 11.5.2 and another on M1 MBA for the M1 MBA.

From a Cold Boot >> Option key and both computers ignore the existence of the Bootable Installer and boot to Log In Screen as if nothing happened.

Once logged In, the Bootable Installer was Recognized and Mounted on Desktop.

Perform the same actions by First enabling Boot from External Drive from Recovery Mode and Presto - will boot from Bootable Installer.