Check the solder joints behind the contact plate. Bad connections will prevent any operation of the lens. This is only a problem where the contacts are joined to a flexible circuit. The ROM in the 50mm normal lenses are soldered directly to the contacts, without a flat cable. These joints can be resoldered, but good magnification and soldering skill is required.
Watch out for that little grounding spring on the right side (photo).

This is the Maxxum 70-210 f/4 zoom lens.