I have a 2011 Yukon Denali XL. The Rear Entertainment 2nd and 3rd row screens just stopped displaying picture. There is still glow with back light and the heat unit works perfectly. They are set to the right source for dvd as well. Checked fuses in the side panel and under the hood and nothing seems to be broken. Tried to reset using the diconnecting negative battery terminal. Also at the same time my rear audio system that control has no power as well. The USB, Cigarette Lighter have power the unit just wont turn on but the front once again will turn on the rear air system just can't change the speed as that is controlled by theis rear unit. Any ideas more than going to a dealer?