Mac Mini 2018 - Cannot boot into Recovery or Internet Recovery. Can only boot into Windows

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Level 1

8 points

Mac Mini 2018 - Cannot boot into Recovery or Internet Recovery. Can only boot into Windows

Hello,

I have a 2018 Mac Mini I've been experimenting with (not my primary system, fortunately). In an attempt to see if I could create a pure Windows 10 install on a Mac, I installed Windows via Boot Camp. Then, using a partition tool while in Windows, I deleted the Mac OS partition and a small partition left over after running Boot Camp. However, I did leave the EFI partition. I then resized the Boot Camp partition to subsume the remainder of the unallocated space. Well, my experiment worked, and the Mini boots right into Windows on power up, and works like a champ (and, Apple just released a Windows HID driver for the ambient light sensor on my LG 5K - sweet!). However . . .

I now want to reinstall Catalina. Before I began my experiment, I created a bootable USB of Catalina with the intent to use Recovery mode. However, the Mini refuses to boot into Recovery, Internet Recovery, or Safe Mode, regardless of any and all key combinations and wired/wireless keyboards. It displays the Apple spinning spoke icon for a few seconds, and then boots right into Windows. I've tried with the bootable USB inserted, and without. I have even tried resetting the NVRAM and SMC to no avail. In fact, I don't even hear any beeps.

Looking for any suggestions prior to submitting a service request. Fortunately, I still have 18 months of AppleCare.

Thanks!

Mac mini, macOS 10.15

Posted on May 13, 2020 2:23 PM

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Answer 1

Best reply

megadude2112 Author

Level 1

8 points

May 16, 2020 6:15 AM in response to HWTech

UPDATE: I solved the issue and was able to boot into Recovery mode. As a desperate measure, and on a hunch, I opened the Windows partition app I had used to delete the macOS partition, and ran a 'Check Drive' on the EFI partition. Lo and behold, it found an error and corrected it. I was hopeful. I shutdown, held down option-R, and held my breath. I saw the spinning spoke icon linger longer than usual, and then my Mini booted into Recovery mode. I am back in business with Catalina.

I want to thank everyone foe their replies, information, and suggestions!

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Answer 2

megadude2112 Author

Level 1

8 points

May 13, 2020 4:13 PM in response to QuickPost

Thanks for the reply!

I followed the instructions here:

https://support.apple.com/en-us/HT201372

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

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Answer 3

HWTech

Level 9

56,402 points

May 13, 2020 8:18 PM in response to megadude2112

Are you trying to boot into Recovery Mode with WiFi or by using an Ethernet connection?

When trying to boot from the Catalina USB installer does the computer allow you to access the Apple boot picker menu? If so do you see the Catalina USB installer as an option? What happens when you select it?

I haven't used Bootcamp in years so I don't recall the procedure. Did you have to disable T2 security to allow the Windows USB installer to boot?

https://support.apple.com/en-us/HT208198

If not, then you may now be in a catch-22 if you cannot boot into Recovery Mode or Internet Recovery Mode.

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Answer 4

HWTech

Level 9

56,402 points

May 14, 2020 10:27 AM in response to megadude2112

Do you have access to another Mac so you can try running Apple Configurator 2 to revive or restore the firmware of the T2 security chip?

https://support.apple.com/guide/apple-configurator-2/revive-or-restore-mac-firmware-apdebea5be51/mac

Otherwise you will need to take the computer to an Apple Store or an Apple Authorized Service Provider to have this procedure performed.

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Answer 5

QuickPost

Level 10

103,329 points

May 13, 2020 3:30 PM in response to megadude2112

Hello,

Macintosh models with a T2 chip (which the Mac mini 2018 has) are more like Apple’s other devices than previous Macintosh models where the operating system (macOS) is strongly bonded to that Mac’s physical chip. This is what Macintosh models with a T2 chip cannot revert to a previous version of macOS. I suspect that since you fully deleted the macOS partition, the system’s firmware is unable to re-install macOS. It also could be due to you using the Windows disk partitioner to erase your Mac’s internal storage device. This is why Bootcamp creates a second partition as so it keeps the primary macOS partition in tact.

How did you prepare the macOS installation disk?

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Answer 6

megadude2112 Author

Level 1

8 points

May 14, 2020 3:01 AM in response to HWTech

Hi,

I'm connected via Ethernet. When booting, no matter what I combination of keys I press, I see the spinning spoke icon for a few seconds, and then it boots into Windows. I do not get a boot picker menu or anything - just boots into Windows.

I installed Windows via Boot Camp, so didn't need a USB installer. Just the ISO image.

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Answer 7

den.thed

Level 9

78,034 points

May 13, 2020 4:54 PM in response to megadude2112

Sounds like you need to start completely over from scratch. Backup the Windows, wipe the whole drive in Recovery, reinstall MacOS, then use bootcamp to reinstall Windows.

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