Nissan: Nissan Sunny drivers door lock problem, haynes manual, door latch

Question
Hi there, i hope you can answer this as it is driving me nuts.

I have a Nissan Sunny LX 5 door hatchback with central locking.  The drivers side door will not unlock with the key or the internal widget/switch thing by the handle.  It is very difficult to turn the key but it does reach the point where the central locking unlocks all the other doors until i let go of the pressure at which point the central locking locks all the doors again.

I have a haynes manual which tells me i need to open the door to fix the lock...but i can't because it won't unlock.  How do i manually unlock the door so i can repair the lock OR how can i repair this lock without needing to open the door.  

I sure hope you can help.

Cheers

Answer
Go through the passenger door and open the hood. Disconnect the battery and try to open the door again. If this wont work then you will need to remove the door panel with the door shut and I will tell you now its a pain in the butt. Once the panel is off you can get to the door latch. You either have a bad latch or a bad actuator.