That happened to my old 550 a few years ago. Garmin does not sell buttons, not would give anything to help or replace it (if outside of warranty). I have to pay $250 and send it in to a company Garmin deals with, and they sent me a refurb unit. All because they have no plans for fixing that rubber button.
“If you are neutral in situations of injustice, you have chosen the side of the oppressor. If an elephant has its foot on the tail of a mouse
and you say that you are neutral, the mouse will not appreciate your
neutrality.” Bishop Desmond Tutu