My parents 04 Liberty has a issue with the door locks on the passenger side. Both door lock knobs will not go down using the remote and even if you try to push them down by hand the wont go down. I took the door panel apart and even disconnected the power to the locks and they still didnt move.
My first thought is a latch issue. Sounds like the latch is stuck if you cant push down and lock it by hand. I'd make sure the lock rod isn't binding or jammed. I've seen some where there was dirt build up on the latch and it just quit working. You could try to unhook the lock rod and try to move the lever on the latch the rod hooks to by hand to see if it moves easy.