I've done this fix on at least 3 MX Masters, just going in through the rubber on the side to remove the switch, since disassembly through unscrewing everything is more work.
Needing to replace the feet every time you open the mouse is pretty frustrating.
This applies to the MX Master 1 & 2.
The MX Master has a "gesture" button under the rubber where your thumb rests.
I don't believe I ever used it intentionally.
But because it is a gesture button, when it fails the mouse no longer responds as it always thinks it is gesturing.
Pull the wire and it is fine, but diagnosing it is rough.