My common solution to boot issues that lock me out is,
Get a USB Live distro (always good to have a backup lying around)
Boot into live distro
Chroot into the broken distro (Arch wiki has an article on this)
Fix any bugs that I can find and/or reinstall the bootloader
Test, repeat until the problem has been found and fixed
Hope it helps any newcomers!
I unfortunately bought a subscription before dickhead made his statement. Looks like I’m with them for a year >.<