The spade connector that goes onto the solenoid is quite weak and frail in it’s engagement, get a test light and see if you are getting current to there when you push the button, if you are then work on improving the integrity of the connection there.
Jump the battery to the starter and see if the starter will crank when supplied…(make sure the damn thing is in neutral).
If you suspect the battery, hook up a set of good jumper leads from your car and see if that cures the issue.
If/when you check the battery lead terminals, check BOTH ends of BOTH leads.