Who would have thought it would be so easy?

A little attention to the reset switch and suddenly we have video and sound, loud and clear.

That means the reset mechanism was the actual cause of the no-video, no-sound symptom on this console.

I still decided to replace the electrolytic capacitors while I had the machine apart.

That is maintenance, though, and should be kept separate from the diagnosis.

The fact that a capacitor is twenty years old does not, by itself, prove that it caused this particular fault.

Still, one apparently dead SNES is back among the living.

Sources