Rear liftgate lock stuck in lock position while open

Rear liftgate lock stuck in lock position while open. Cannot close.

 

Get a small flat blade screw driver or pick and try to move the inner latch mechanism on the door. Some WD40 may help to loosen things or the gunk assuming nothing is broken

 

Does it lock and unlock with a key or doesn’t move at all? If stuck completely try what aggrex said, but if locks/unlocks with key maybe the automatic locking tab came loose or needs replaced.

 

A photo would help.
When I bought my Jeep it was a fixer upper, and had been driven in the winters in Ontario, Canada. Road salt had seized up all the locks and none worked, although they were seized to the unlocked position fortunately. I’m no locksmith, but after trying to get them unseized on the Jeep with various elixirs I finally removed one and took it apart. The little tumblers inside the lock cylinder were completely oxidized and frozen. I soaked the disassembled cylinders overnight in rust remover, and gently pressed out each tumbler using the correct diameter machinist’s punch. A small drill bit would work too, using the drill end. I was careful to keep track of the order of their removal as this determines how your specific key pattern moves the tumblers and opens the lock.
I was successful! It requires patience and perseverance but locks can be repaired. Now all my locks work, and I’m still using the OEM keys.
You can do it, good luck!