I had an issue once, but it was after I put the car in a diagnostic mode via the buttons on the steering wheel. I forget exactly what it was or how I got into it, but it was a test mode for checking switches and the LCD screen. Anyway, I figured I didn't exit properly which messed it up, so I went back into the mode, exited, and everything went back to normal.
Not sure the diagnostic mode would help with the problem if the only issue is with the backup camera. However, it seems to me it might be a connection issue as was mentioned...loose connection or water penetration.
I have had some odd issues that seem to be fixed with a power cycle...i.e. pull the fuse or the 12V battery. My car's cruise control has gotten into a weird state on 2 occasions. The controls didn't quite work as expected and I would eventually get a yellow wrench on the display. The first time it went away on its own but came back a few months later. I decided to disconnect the 12V battery momentarily and that solved the problem a year or 2 ago and I haven't seen it since. I've had the radio stay on after turning off the car on 2 occasions and pulling the fuse for a second or 2 solves that problem.
A lot of the cars components are connected via CAN bus so it doesn't surprise me too much when a module stops responding. But that's now in my arsenal for FFE debug....cycle the 12V power before taking it to the dealer. I also have my Forscan software and OBDII module now too.