If anyone is wondering...
This sucks. Rewired the whole system, 2 seperate harnesses, I'm told. New cameras all around. New module, I guess behind the seat. New camera in the windshield. Two more times at the dealer for that. Yesterday waited on it to get wrapped up. Drove off the lot, stopped 10 mins down the road, put it in reverse--- the black screen with the triangle and exclamation mark.
This is beyond infuriating at this point. I don't know what to do either. The dealer says they've talked to "GM", I've opened a case with GM customer care, but I think its obvious they aren't communicating with one another because of things each have said the other is working on, but nothing happens.
I hate to trade it, but that's what I think my only real option is.