Thanks a ton for putting the effort into this post
Been a few years, but I read this thread a couple of times while searching for DIY instructions for replacing/troubleshooting backup camera on a 2011 Yukon XL.
Checked the fuse. Good. Checked the mirror power. Good. There is some control module somewhere apparently, didn't find that..I assumed also good. Then took a leap of faith and figured that somehow the camera just simply went on the fritz after 8 years.
NoWayMan, your suggestion to look on eBay was gold. I found an applique for cheaper than I could find a replacement camera (which as we can deduce from the posts above was never meant to be replaced) and that saved not only money, but a huge amount of time.
Next, I found this video and it walked step by step through the removal and install.
I suspect there were a few edits made to the video where he was cursing at whoever put the locktite on some of the threads, but it all came out OK and I broke nothing in the end.
Good luck to whoever finds themselves in a similar position. It's not so scary a procedure after all!