Have you checked the wires inside the rubber boot from the door to the body?
This is where I've seen 99% of mirror-no-work problems at my shop. The bending
of the harness every time the door opens eventually will break the wires. Pull
either end of the boot loose, and tug gently on each wire- you will probably
find a few broken. Splice-solder them (first slipping a short pc. of heat-
shrink tubing over the wire), and all will be well again, hopefully!

 Karl~