Diagnosis
Moisture or grease has seeped under the capacitive touch panel, shorting the circuits. This is common if the top was wiped with a wet cloth.
How to Fix It
Unplug the unit for 24 hours to let internal moisture evaporate. During this time, wipe the control panel bone-dry with a microfiber cloth. Plug it back in. The buttons may return to normal.
If That Didn't Work
The control board or the touch panel ribbon cable is likely faulty. This requires a warranty service or board replacement. Spilled liquids can cause permanent damage.
Heads Up
Clean the exterior with a slightly damp cloth only. Never spray cleaner directly on the unit. Always wipe spills on the control panel immediately.