I have an RPi 3B and have had it powering an RPi display for a few years. I recently reimaged my card using dd from another Pi+display combo that was working perfectly and tried to boot the system with both the source and the reimaged card. The display turns on when I boot the pi, shows the for red raspberries and then promptly goes black before showing me any text during boot. The pi boots perfectly fine because I can SSH into it and it seems to be fully functional, but the display stays off.
I know for sure it is not a power issue. I have used this power supply for a long time successfully and tried swapping to a new higher current one and also tried powering the display and pi separately. All with the same result.
I tried the reimage with a couple different cards. Same behaviour.
System is running Raspbian Stretch and is up to date.
Any tips on what I can investigate?