My ge microwave displays a message " keypad has

The only way possible to see if the touch pads are working is to test the voltage of the control pads when it contacts. The input of the Microprocessor should be checked for the pad control impulse to come in. If there is no trigger voltage to the mP this can be the control pad problem.Some dirt can accumulate and cause the tracks to short resulting in this display. Try to use heater to warm off any moisture.
The mP must be checked for the working voltage and also the frequency oscillation at the crystal leads. If so the mP is working with a suspected control pads which are not able to set the program or timing.
There is no way but to remove the sticker pad and replace, One difficult way to have a chance is to remove the carbon sticker pads and check continuity , You can use a carbon pen to line the tracks so that the multi-meter reads a continuity. With this you can have a temporary fix