if you have a keyhole in the door you can do a manual unlock by holding the handle in the open posittion and using the key to turn the lock. This is the work around when you get a dead battery but if your is like mine where there is only a keyhole on the driver door then you may have to take it to the dealer because it sounds as if the power to the lock on that door only is somehow disconnected.

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Robert

1994 740iL
2001 X5 4.4i Sport
2004 Kawasaki ZX-6R
2009 VW Jetta S