You could try booting from the LE Live disc, then when that is fully loaded, remove the usb drive and select reboot. If that doesn't work you should at least be able to access your LE install from the live environment and recover/debug from there.
I have been having your same problem since installing 12.0.2, on fairly different HW: an HP stream laptop... so probably not a gpu driver issue. Calling up the boot menu on restart and then manually selecting the install drive also works for me. I am guessing a boot manager issue?