I've got an '03 SE7 with 49500 on the clock. Went out to it to put something in the back and the handle would not work. Tried to lock/unlock multiple times and retried handle, no luck. Climbed inside and tried to use the door handle form the iside it moves and pops up the lock button, but the door still will not open. All other doors/locks are working fine.

Any thoughts?

Thanks in advance (I tried the search function but didn't come up with any similar posts).

 

You can try removing the LR badge on the tailgate handle and spray silicone lube in there.

 

Do what Disco2Guy said first. These needs to be done every 6 months at least. More often if you drive in dusty conditions.
If that doesnt do it then your rear door latch mechinizumiminmimmmm might be bad.
If the child lock is on then you can open it from the inside.