The numeric buttons and the start button on my microwave touchpad do not work, nor do the auto programed buttons like "Defrost" or "Melt". The display is illuminated and shows the correct time, and the manual programming buttons react to touch, but without the numeric buttons working, the manual functions cannot be programmed or started. The light inside the microwave is also not working. The touchpad and light failed all at once, it was not something that got progressively worse. The door latch is working properly.
Is the problem in the membrane or the control board or...? How can I test the suspect parts?