DIAGNOSIS Unresponsive touch controls are usually caused by a greasy or moist control panel film. Fingerprint grease and cooking steam can create a non-conductive layer.
FIX Power off and unplug the unit. Let it cool. Dampen a microfiber cloth with a small amount of isopropyl alcohol (rubbing alcohol). Gently wipe the entire touch panel. Dry thoroughly with a clean cloth. Do not use water or spray cleaner directly on the panel.
IF THAT DIDN'T WORK The control panel's ribbon cable inside the unit may have come loose from the mainboard due to heat cycling. This requires disassembly and is a task for a technician or support.
HEADS UP Always operate the controls with clean, dry fingers. Wipe the panel down after every few uses to prevent grease buildup.