Band button won’t work

The usual fix is to run gently warm water (not hot) over the problem side while you manipulate the button with your fingers (no hard tools please) and try to jiggle the band in its groove. Just keep working at it, you might need a little time but you will win.

Yes, keep trying because there is nothing else you can do!

When the button is out (not pressed) it should be exactly flush with the body of the watch. When it is pressed in it will be about 0.5mm below the surface. There is not a lot of movement, but it will be visible.