5500 board won't POST/chime w/o the Display hooked up?

[Trash80toG4]

I've got a test rig that'll boot Alchemy and Gazelle boards with no problems at all, but not my AIO 5500 sub-variant of Gazelle. Does it fail to POST due to lack of internal CRT hookup or might there be another issue with this particular board?

If display is indeed the problem, will it POST with the external display/projector cable installed in lieu of the checking for function of A/B CRT hookup during POST?

 

[Trash80toG4]

Dug my 6500 board out of the Classic it's been sitting on its head in for two decades. It powers up/chimes, but no video out for some reason. I'll dig out the proper two story Video Out/Sub Driver variant and see if that makes a difference, doubtful, but another base to cover.