Quick summary: I tried to install Big Sur on a Macbook Pro (Retina, 13-inch, Mid 2014) but this failed and now I can't access it anymore. Now I'm trying to access it through Recovery Mode to back up some files, but the FileVault password claims to be incorrect. Any ideas?
Midway through the macOS Big Sur installation, a message popped op saying "An error occurred preparing the software update", only giving me the option to restart. Now the device still starts up normally to the login screen, but when I sign in with the user, it ends up with black screen and a prohibitory symbol. Accessing the Mac in Safe Mode (Shift) or Single User Mode (CMD+S) both failed in the same fashion.
I presume the only way to do anything is through Recover Mode. Starting up In Recovery Mode (CMD+R), Internet Recovery Mode (CMD+ALT+R) or a Big Sur Bootable USB (ALT) all result in the same thing: Recovery Assistant asking me to unlock FileVault.
The default password to my account does not work; it claims to be incorrect, even though it's not (100% certainty, it only consists of a few numbers). Different keyboard language settings have no effect. I read this might have something to do with Administrator rights being disabled during installation, and I also read a SMC reset might do the trick. Unfortunately, no luck.
The other option is to sign in with an Apple ID. If I use the Apple ID assigned to the user of the Mac, when I hit "Unlock Account", no Two-Step Verification is send to another device; it just says "An unknown error occurred". When I use a completely different Apple ID, it does send a Two-Step Verification request, but when I approve and enter the 6-digit code, it says "The supplied iCloud account was unable to unlock this volume" (obviously).
Does anyone have any ideas on how to unlock FileVault and access the disk?
Midway through the macOS Big Sur installation, a message popped op saying "An error occurred preparing the software update", only giving me the option to restart. Now the device still starts up normally to the login screen, but when I sign in with the user, it ends up with black screen and a prohibitory symbol. Accessing the Mac in Safe Mode (Shift) or Single User Mode (CMD+S) both failed in the same fashion.
I presume the only way to do anything is through Recover Mode. Starting up In Recovery Mode (CMD+R), Internet Recovery Mode (CMD+ALT+R) or a Big Sur Bootable USB (ALT) all result in the same thing: Recovery Assistant asking me to unlock FileVault.
The default password to my account does not work; it claims to be incorrect, even though it's not (100% certainty, it only consists of a few numbers). Different keyboard language settings have no effect. I read this might have something to do with Administrator rights being disabled during installation, and I also read a SMC reset might do the trick. Unfortunately, no luck.
The other option is to sign in with an Apple ID. If I use the Apple ID assigned to the user of the Mac, when I hit "Unlock Account", no Two-Step Verification is send to another device; it just says "An unknown error occurred". When I use a completely different Apple ID, it does send a Two-Step Verification request, but when I approve and enter the 6-digit code, it says "The supplied iCloud account was unable to unlock this volume" (obviously).
Does anyone have any ideas on how to unlock FileVault and access the disk?