
Luckily, I came across a strange but working temporary fix using a windows bootcamp installation posted by Milangoa in this thread: Now I just need to figure out how to restore my Bootcamp image from a DMG file. Let it reboot and migrate everything from the external drive back to the internal drive. Go to Disk Utility and completely wipe the internal drive. Verify everything transferred OK to the external drive. Migrate everything from the internal drive to the external drive when it prompts you. Let it boot up the MacBook from the external drive. Go to disk utility and reformat the external hard drive as APFS.Įxit disk utility and reinstall Big Sur on the external drive. Use internet recovery (Hold Command + Option + R during startup). I formatted it to exFAT on my Windows desktop. Since I didn't have enough drive space, this is how I fixed it. I even deleted my Bootcamp partition (after saving it as a DMG file), but it wouldn't let me merge that drive space back into my Mac partition.

You might be able to get away with just using internet recovery if you have enough drive space on your internal drive, but for some reason, it said I didn't have enough space. It was stuck on the loading screen, and wouldn't move past it even after several hours. I think it auto-updated to Big Sur and bricked my laptop.

I had the same issue on my Late 2013 Macbook Pro 13 (A1502).
