Idk but if you're still willing to try a few more ideas in the name of science...
I know you said you tried other options at the boot screen but did u try this:
Enter boot screen. Short press power button, fastboot should go to the top. Use vol down to select "reboot bootloader". Short press power button. Screen will flash off then come back on after a few secs. Then arrow down to reboot. Short press power button and see what gives. If that fails, at the start of the next boot cycle, hold vol down and the trackpad button at the same time and see if it'll boot into safe mode for kicks.