[floatingkiwi]

Did you have a problem with a bad battery? Cause that'll do it.
I've been in mine many times (due to battery problems) and they are a pretty simple mechanism (mechanically) but the electronics that drive the actuator motors are quite tricky sequence-wise. i.e when you press the drivers lock down it passes a contact that signals the a high voltage condition for both doors that serves to then lock the passenger side etc etc.

Sometimes mine will work and sometimes not - for the life of me I can't figure out why.

Anyway, what I can tell you is if the lock is stuck halfway down then what has probably happened is that the lock lost power at some point during the lock cycle. To fix that you need to remove the lock mechanisms (the black box) and open them up and turn the little motor around until the contacts are back in the right spot - sounds tricky but you'll see when you open it up. Once you've done that if you get a 12V DC power supply and just check that the lock is cycling when you touch the wires to the motor contacts it should be working OK.

Of course this is assuming you don't have any sort of mechanical seizure.

Matt