So you rolled back your root filesystem’s system state to a snapshot but did you roll back the kernel you’re booting into aswell?
If you didn’t, that’d explain the symptoms seen here; you might be booting into a newer kernel than the system state has modules for. Without the appropriate kernel modules, Linux cannot mount filesystems or accept keyboard input. (This depends on which modules are required by the HW and whether they’re built into the kernel or copied to the initrd though.)
For debugging, simply boot a live ISO and chroot into the system. The Arch Wiki has a page for that. You should be able to look at the journal inside the chroot and it’ll tell you exactly what’s wrong.