Two common faults in microwave ovens are mostly related to membrane switches or FPC printed circuits.
(1) Most of the key switches in the keyboard fail. This failure is usually caused by the leakage of the membrane switch or FPC. The electricity leakage is caused by long-term moisture or moisture erosion of the microwave computer board and it is sometimes difficult to judge whether there is electricity leakage from the appearance of the circuit board. Therefore, if necessary, it will be effective in most times that you directly use absolute alcohol to wipe or clean the membrane switch, FPC and computer board. This kind of failure may also be caused by several disconnections in the FPC printed circuit at the same time, but these disconnections are basically caused by improper maintenance, so they are not common. When checking, you can quickly check the fault by just seeing with the naked eyes or measuring with a multimeter. Then as long as you re-solder the broken wire, the fault can be eliminated.
(2) Individual key switches in the keyboard are malfunctioning. The main reason for this failure is that the FPC circuit corresponding to the failed switch is broken or the membrane switch is in poor contact. You can find the membrane switch corresponding to the malfunctioning switch and repair it.
The failure of the microwave oven buttons is probably due to the aging of the membrane switch panel. If it is more than four years, it is recommended that you replace the membrane switch panel, and it is OK as long as you replace it with one of the same model and specification. This replacement can be done by removing the control panel by people as long as they have basic operational ability. If you can't buy a membrane switch panel, you can also change it to a micro switch. The circuit should be wired according to the old membrane switch board, and the panel can be done by drilling holes, installing micro switches, fixing and wiring with silica gel.
After the microwave oven is used for a long time, the membrane switch may be aging. In this case, the switch that are used with longer time is really not useful, so there is no need to spend money on repairs, and you can replace the membrane switch panel. If the membrane switch fails when used for short time, then it is necessary to see if the machine is affected in any way, such as whether it is damp or corroded by water. These problems are required to be studied carefully.