Contact cleaner probably found its way to under a pad (impressive as it would be on the opposite side but within reason, especially if there is a support/screw hole nearby.
Anyway solution is likely going to be take it apart, clean the button contacts and try again. You could try pressing the button a few hundred times, and a kind of hard press or three in among those as well, but that is less likely to be effective than a clean. Bonus is you already have contact cleaner by the sounds of things.