I havent seen any failures that I could attribute to temperature of any kind, internal or external, on a personal note, it gets into the "one teens" here in Fresno which means the inside of my car is REAL HOT and Ive had no heat failures in my cars in the 3 summers I have had dynavins.
I would guess its just coincidence. Based on your description of the issue it actually sounds more like the ribbon cable that connects the screen to the main unit might be loose.....in which case it was loose before you parked but being heat cycled in the parking lot might have just been enough..... Since you have a good electrical background and you are out of warranty anyway, I would suggest you check all the ribbon connections, you might just solve your problem.
Also what happens when you press the Nav button, since it is a split system it not likely that BOTH sides failed.
Last edited by jeffb335; 06-26-2012 at 02:13 PM.