Diagnosis
The primary cause is a failure in the touchpad membrane switch assembly or its connection to the main control board. This is frequently triggered by moisture from steam or spills seeping into the panel, or by a physical impact. The issue is almost always within the control panel area, not the main board itself, as other microwave functions would likely also fail if the main board were faulty.
How to Fix It
First, unplug the microwave from the wall outlet. Have a helper support the unit while you remove the two mounting screws at the top front of the cabinet. Carefully lower the microwave to access the rear panel. Remove the screws securing the rear metal cover to expose the control panel's ribbon cable connector on the main board. Gently unseat and then firmly reseat this ribbon cable connection. Reassemble, plug the unit back in, and test. If moisture was suspected, allowing the unit to dry completely for 24 hours before reassembly may resolve it.
If That Didn't Work
The touchpad membrane itself is defective and requires replacement. You must purchase the specific touchpad assembly for the ME19R7041FS model. The part number (e.g., DE93-00546A) is usually printed on the back of the faulty membrane. After gaining access as described above, disconnect the ribbon cable, remove any screws or adhesive securing the old panel, and install the new one, ensuring the ribbon cable is locked into the connector on the main board.
Heads Up
The microwave is very heavy and can fall; a helper is essential for safety. Always confirm the power cord is unplugged before starting. If you are not comfortable with this repair, contact a qualified technician, as improper reassembly can create a fire hazard or risk the unit falling.