So the rear hatch won't open or the rear window won't open?
Before you take it in, try to unplug the negative battery terminal and leave it off for 15 minutes. Reconnect it and you may have to reprogram things like the auto up/down windows auto-close/open sunroof, radio etc. Then try the rear hatch...
"resetting" the truck has solved some wierd problems before so it's a quick and cheap thing to try...