I've run out of ideas and hoped someone can help

N/S rear door won't unlock/open either from inside or outside. All other doors are fine.
It appears to be a mechanical problem as I have even tried disconnecting the battery.
I have now managed to remove the inner door card (not easy with the door shut.......took pics so can produce a guide, without breaking clips

) and the plate so that I can get at the back of the module but I'm not sure that has helped.
I can't see what needs to be operated or moved to open the door.
I'll upload some pics that show where I am now..............