Hi, I had the same problem(I'm assuming your battery is flat) I think your mechanics wrong, if its got central locking you need power to open the door. On my 730 what I did was pull up the door handle on the PASSENGER side then turn the key forward in the lock past the point at which it feels as though it will go no further(I had to use an anxiety inducing amount of force..) the lock should pop open. One caveat. my car is right hand drive, I don't know whether that means it would be the drivers side door on an american version?