I removed everything from the car and brought it back to the workstation.
Back on the workstation I could not get the screen to power on. I had to reset the CMOS to get it to work again. Took it back outside powered up, saw the Windows boot screen again and then... blank screen again and could get a signal on the next boot.
Why would it do this when I power it from the car??
On a far outside chance I'm wondering if it was the sabrent TV card I installed. I did remove it for the second round of boot/blank screen. I wonder if the drivers or something has anything to do with it. Next step is to remove them completely. I don't have a restore point, but that would be nice. Still, this only happens when the system is powerd by the car.
This is frustrating...
