Very late answer, but adding as i’ve just fixed the same issue. You can actually remove the button, as it is glued on (from the outside) and then has a clip on the inside. To do this you’d need to teardown the watch to it’s componants (follow this video https://www.youtube.com/watch?v=r1as_h5j...) Once you’ve removed the clip on the inside of the button you can push it out, clean it throughly and then pop it back in, pop the clip back on and it should work.