yep, take out the mechanism, its a bit fiddly, now take out the small screws and inside you will see a motor, this sticks for some reason, spin it by had a few times, reconnect the power and try it to see if it works, dont be put off as it can take a few goes to get it to work.
before this tho try to lock all doors with the passenger internal lock on the door sill, if this doesnt work clean the connections to the door mech. try again. if not working try above. if on the first attempt it did lock the other doors, take off the door card and retry, it could be stiff on the door card and stop it opening on the fob button!!
hope this helps