Having a problem where the EFIS frequently does not boot up correctly. This occurs even with no USB and no SD card inserted. It also occurs whether the unit is started with the Master switch or by holding Button 1 on the EFIS (the EFIS does have a backup battery wired). When turning on the EFIS, one of three things happens:

1) The system boots up normally (less than 50% of the time)
2) The AFS logo appears, the screen flashes briefly (I believe this is the GRUB boot loader screen), then the AFS logo returns. No progress is made after this, the unit seems to be hung.
3) The fan comes on, but the screen stays dark.

What is the best way to debug boot-up issues? We have already run through the BIOS settings changes as recommended by AFS. For #2, would it be possible to see kernel boot-up messages instead of the AFS logo? I have no idea where to start for #3...