Monterey on MBP 9,2 won’t boot after installing OCLP 1.5.0 to disk

After some trial and error, I finally managed to install Monterey on my MacBook Pro mid-2012 9,2. When I get to the part of installing OCLP to disk so as not to have to keep the USB inserted, it just gets stuck on the white Apple boot screen with a progress bar that goes nowhere.

I am at point 22:21 in the u/MrMacintoshBlog video

https://youtu.be/-huRykhjs6g?t=1299

I held down Option while restarting and then held Control along with it, so that EFI Boot would be the default boot disk. But when I try to boot into Macintosh HD, all I get is this screen and it gets stuck. Zapping the PRAM didn’t work, and neither does trying to start in Safe Mode. Please help: How can I fix this?