I've committed a cardinal sin, I messed up. There, the elephant is out of the room. In a rush to get the playfield back into my Williams Comet and play a game, I hooked up the black playfield connector to the white backbox connector, and same with the white playfield connector to the black backbox. They are unfortunately the same size and keyed the same way, but the colors should have tipped me off.
I was able to get some good pointers from this thread -
https://pinside.com/pinball/forum/topic/space-shuttle-wont-boot-error-code-7-williams-system-9
But the suggestions were pretty general on what I likely broke. The symptoms now of the game are a 'system failure', or 7, on the MPU. Looking at the schematics, I can't figure out what to start replacing. I would appreciate any pointers anyone could offer that has maybe gone through this themselves or for a customer. I have some experience replacing PIA's and would like to give it a try myself first. Here is a link to the schematic -
http://www.planetimming.com/Pinball/space_shuttle_williams_1984.pdf
Thanks in advance!