I thought there was something up in the Faq's, but I couldn't fine it.
This is not an uncommon problem. Open the rear window and remove the four top screws that hold the rear panel in. Then you'll need to pry the panel out just enough to see the locking mechanism at the bottom. Don't pull to hard or the panel will crach. I stuck a piece of 2x4 in between the panel and the hatch so I had both hands free. With a flash light, look down at the lock mechanism. I then cut the top of a hanger off and stretched it out into a long staight line. I made a small U shape at one end. I guided the 'U' end down to the locking mechanism and once I captured the lever, I pulled up and released the lock. When the hatch opens, remove the rest of the panel. There will be some hidden screws in the bottom carpeted corners. Feel for them. Once the panel is off, the locking mechanism will be exposed. You will see a threaded rod that is attached to the handle. That rod is captured by a metal clip. The clip looses grip on the screw rod and slips. That's why the door won't open. Adjust it until it functions properly. I used some safety wire to wrap around the screw rod once I had the adjustment correct. That will prevent the rod from slipping in the future.
[B]2008 Jeep Wrangler X[/B] (Hard Top)
Incubus Off Road 511's with BFG 285/70-17
[COLOR="White"][B]1998 Jeep Cherokee Sport[/B]
4.0L/AW4, Yakima Roof Rack[/COLOR]