My guess:
- Fuse
Or
- Seized motors inside mirror itself. (Spray a bit of wd40 in behind glass & try to move glass to see if motor will kick start).
Or
- Corroded connectors from mirror to harness in door. (Remove door cards & check connectors, plug & unplug a few times to help clear any corroded terminals).
Or
- Corroded connectors running from door jamb in to door. (peel back the rubber boot covering the cable harness & pray that you don't see a load of corrosion!)