[iotg][tgl-aaeon] System does not cleanly restart after cold reboot test

[Summary] Checkbox runs a stress test to perform a cold boot on the DUT a number of times. After the system shuts down, the system should restart automatically, and come back up cleanly. Devices, video, network, etc. should all come back up.

However on this board, the system does not restart cleanly. The screen is blank, except for a single blinking cursor. No prompt. No login screen. Just a blinking cursor.

This is using the IOT daily build from September 24 or so.
https://cdimage.ubuntu.com/focal/daily-preinstalled

[Steps to reproduce]
Use CDTS remote to start the cold reboot tests.

[Expected result]
System should cleanly shutdown and restart. CDTS will resume with the next cycle.

[Actual result]
System shuts off and does not restart. You must hit the power button to restart the system. The graphics do not come back, all you get a blank screen with a blinking cursor. Network comes back, so I was able to ssh in and file this bug.

[Failure rate]
100%

[Additional information]
CID: (applying)
SKU: TGL-Aaeon-1
system-manufacturer: AAEON
system-product-name: UPX-TGL01
bios-version: 5.19
CPU: Intel(R) Celeron(R) 6305E @ 1.80GHz (2x)
GPU: 00:02.0 VGA compatible controller [0300]: Intel Corporation Device [8086:9a78] (rev 01)
kernel-version: 5.13.0-1004-intel

[Stage]
Issue reported and logs collected right after it happened