The controls and indicator lights have worked erratically for several months. Some buttons would work some of the time. By unplugging the power and letting it sit overnight, I was able to get it to run, but all of the buttons and indicator lights were not working correctly. I tried the "reboot" process once, but that did not seem to change anything. The latest development is that nothing works except the Cancel/Drain button, which runs a two-minute drain cycle. I took everything apart, cleaned the ribbon cable and connections, but that did not help. There are no obvious burn marks anywhere. I cannot find a wiring diagram anywhere that would let me use a continuity tester to test the keypad on the control panel. How can I determine which part to replace?

See the attachment for the tech sheet. It has the keypad pinouts.

I really appreciate the attachment, but I am not enough of an electrical engineer to decipher it. Do you think it is more likely the keypad, or the control board?

Interesting. After heating up and pressing all the buttons repeatedly, the Cycle-Light button now works, meaning when I push the button, the Indicator light comes on. No other buttons work. When I use the Cancel button, it goes off. But the dishwasher will still not run because no other buttons appear to work.