It was a faulty controller board. I got my replacement board today and the keyboard is working again. But, damn! mounting that board is an exercise in frustration!
Anyway, I believe that the capacitor (I'm guessing) in C17 in the image has somehow deserted the board. In my replacement board it's there. Now I would like to know what kind it is, so I can try to put a new one in it's place and have a working spare controller.
Unfortunately I'm not able to provide better pictures. This is as close as my current camera and lens will take me.
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