MBPro doesn't boot in Recovery Mode

Hi Simon,

Please note that on Apple silicon Macs, disabling or customizing System Integrity Protection will automatically downgrade the boot security policy to Permissive Security. Returning to Reduced Security or Full Security will automatically enable all of SIP again.

In order to disable or customize SIP, you will need to boot from the copy of macOS Recovery that is paired (associated with) the target macOS installation. Follow these steps:

1. If you have multiple copies of macOS installed, go to System Preferences -> Startup Disk, and set the macOS installation you want to disable SIP for as the default startup disk. (This is done in order to satisfy the pairing requirements.)
2. Shut down your MacBook Pro.
3. Press and hold the power button (Touch ID) until Startup Options begins loading.
4. The Boot Picker screen should now appear. (You're already in macOS Recovery at this point, but choosing a startup disk here will boot it immediately.) Select Options and click Continue.
5. macOS Recovery should now appear. If prompted, authenticate with your admin password to continue.
6. The main utilities window should now appear. At the top of the screen, select Utilities -> Terminal.
7. Run one of the two commands below:
   1. To only disable filesystem protections, and keep the rest of SIP enabled: csrutil enable --without fs
   2. To completely disable SIP: csrutil disable
8. If you have multiple copies of macOS installed, indicate which macOS installation you wish to customize or disable SIP for.
9. Enter your admin credentials when prompted. Terminal won't show anything as you type your password.
10. If successful, csrutil will report that System Integrity Protection is enabled (customized) or disabled. You can safely restart your Mac at this point.

To re-enable System Integrity Protection, choose one of these options:

• Complete the above steps again, but run "csrutil enable" in step 7. It is strongly recommended to return back to Full Security when prompted.
• Complete steps 1-5, but choose Utilities -> Startup Security Utility instead. Then, choose the security policy that works best for you.
• If you want to switch back to Full Security as quickly as possible, you can run "sudo bputil -f" while running regular macOS.
• If you want complete control over the boot security policy, read the man pages in Terminal for bputil, csrutil, and kmutil [configure-boot].

majortom1967 wrote:

... Whenever I choose the internal disk (simply "Macintosh HD") the machine restarts instead of giving me the HD'S options.

Perhaps I am misunderstanding you, but that's not how you accomplish what you seek. Don't choose the startup disk; choose the "gear" icon.

1. Start with a Mac powered on in the usual manner, logged into your User Account.
2. Shut down the Mac using  > Shut Down...
3. Wait until the Mac actually shuts down. You can confirm it has actually shut down by pressing the Caps Lock key. The Mac will begin to start, but the Caps Lock LED will not illuminate until after the Apple logo appears. If that did not happen then it was not shut down, so you might as well start over at Step 1.
4. Press and hold the power button / Touch ID button. "Continue holding for startup options..." will appear, followed a second or two later by "Loading startup options...". If that does not happen, you might as well start over from the beginning.
5. When the "hard disk" and "gear" icons appear, release the power button.
6. Select (momentarily click) the "gear" icon. disk. "Continue" will appear beneath it.
7. Click the Continue button to open macOS Recovery.

From there, you will be able to open the Startup Security Utility from the Utilities menu.

Use macOS Recovery on a Mac with Apple silicon - Apple Support

majortom1967 wrote:

Hi, I need to temporarily disable SIP and therefore to choose my main internal disk from the boot options (icons) in the boot mode while holding down the power button. Whenever I choose the internal disk (simply "Macintosh HD") the machine restarts instead of giving me the HD'S options.

The MacBook Pro (16" - 2021) ha already been reinitialized once.

I thinking to erase the whole disk via terminal and reinstall via the net but I'm wondering if there's any security "trap" around or reinitiaize via DFU mode.

Thanks for any help.

Simon

And what is the purpose of disabling SIP...?

Recovery is reboot w/ Command R or Option Command R

https://support.apple.com/guide/mac-help/macos-recovery-a-mac-apple-silicon-mchl82829c17/mac

If your Mac starts up to Options with a gear icon - Apple Support

majortom1967 wrote:

What if I delete it completely via terminal (they do it in Apple Stores) as external HD? Will I be able to reinitialize the machine via internet?

Tnx.

No matter how badly you brick your Apple silicon Mac in terms of software, you can always restore it back to factory condition using a second Mac with Apple Configurator: Revive or restore a Mac with Apple silicon using Apple Configurator - Apple Support (CA)

Note that if you choose to perform a DFU restore, you could be locked out by Activation Lock. To clear Activation Lock after the restore, provide the previous Apple ID and password used, or the Mac login password of the user that enabled Activation Lock.

Also, can you please explain what you mean by the HD option? If you select your internal drive (Macintosh HD) in Startup Options, your Mac will proceed to immediately restart and boot that drive, instead of continuing to macOS Recovery. Perhaps that looks like a machine crash??