I just opened up my G935s and repaired the main switch. It apparently got dust, oils, or some other contaminant inside. Six small screws to lift the panel out of the cup, be careful with the speaker diaphragm wire, it's soldered on both ends. Carefully unfasten the clip that holds the C-shaped daughter board to the smaller LED light one, and speaker+C board should lift out. Carefully remove the metal cover on the switch, it's fastened like a flat circlip, once you remove that, the black plastic switch lifts out of the switch housing. Clean contacts well in switch body and switch module with isopropyl, reinstall without getting any grease or dust in there. The flat circlip snaps back in place, I needed a small screwdriver to poke the ends into place/seat them. Then just same steps in reverse to reassemble. Be careful getting the C board back into place, it's fiddly, but can be done without force.