I'm trying to reinstall macOS to a seriously messed up MacBook Pro 2018. Apparently, problems started initially when the Big Sur update failed. The computer's disk has since been erased and all accounts have been lost. The computer shows a question mark folder when it's started.
Here's what I've tried so far:
- Started Mac to startup manager (press Opt in startup). No disks are showing, the only option is internet recovery, which fails.
- Started Mac in recovery mode and ran First Aid on the disk, which says that the volume appears to be OK. In addition to internal Apple SSD, there is a macOS Base System Disk Image.
- Also in Recovery Mode, I've run the command
bless --getBootwhich both return
Can't access "efi-boot-device NVRAM variable.
- Reset NVRAM and SMC, which had no effect
- Tried to install macOS from a bootable drive, which failed because the external boot is disallowed in Startup Security Utility. I cannot change the setting because there is no administrator account.
- Tried to start into single user mode (Cmd+S), to remove
/var/db/.AppleSetupDonefile in order to run Mac setup again and get new admin account. Logging into single-user mode fails, apparently because there is no startup disk (based on Unable to enter single user mode (to create Admin account)).
- Tried to set startup volume in recovery mode terminal by running command
bless -mount /Volumes/Macintosh\ HD/ -setBootwhich returns the following:
Can't load /Volumes/Machintosh HD/usr/standalone/i386/apfs.efi Could not load apfs.efi data from /Volumes/Machintosh HD/usr/standalone/i386/apfs.efi
Any ideas on what I should do? I'm guessing that the first thing I need is to get the startup disk working and create an administrator account. However, that seems to be easier said than done.