Bosch built-in microwave hmt85g650b.
This one the buttons have a micro-switch behind the button.
Unplug.
Remove from cupboard. Screws on front stop it being pulled out.
Remove metal casing.
Remove two screws at either end of front lower panel. Keep the rubber seal and note how it fits.
Disconnect ribbon cable.
Push panel up slightly and ease out.
You need to remove the PCB from the plastic case. So remove the two screws and push the three tabs. This exposes the PCB. Push tabs keeping PCB in starting at opposite ends working towards middle.
Once the PCB is out check each micro-switch for movement. Resolder any that move. If none move replace as they are cheap and easy to get hold of.
Fit in reverse. BUT check the earthing between case and front panel. Don't forget the rubber seal.
Don't run the microwave without the casing on and be very careful where you poke the screwdriver as some of the parts will hold at least 4k volts for quite sometime before they naturally discharge.
If in doubt get someone else to do the fix for you.