I just reinstalled the central lock on my car and had the opposite happen.The door would lock but not unlock.Drove me crazy for a little while.Could not find any break in any of the wires,anywhere.You will need to take off the door panel.Also be prepared to get some nicks and cuts,it's a very hazzardous in the door cavity.After moving some wires around while I tried the key I finally found the my problem, a loose connection near the top of the switch that wraps around the lock cylinder.I got lazy and just wrapped some electrical tape around the entire top where the wires are and it worked so I left it that way.Maybe not a proper repair but hey it works and no more cuts on my hands!Your milage may differ!