The controller that came with my Xbox One S has a finicky A button. It registers a press maybe 7 out of 10 times. It's been that way from the day i bought my S console. You may, or may not, have read my post about buying an Xbox One S. I bought and returned 4 directly from Microsoft. Every single one had an annoying grindy fan. Making this even MORE annoying is the fact that the fan slowly spins even when the console is off! Since it is on my desk about 2.5 feet from my head i had to buy a switch to fully disconnect it from power. The constant grinding is unbearable lol. Anyways, I just gave up and kept the 5th one because i wanted to play the Master Chief Collection with my brother Co-Op.
I did a little digging and it seems this A button thing is a common problem with the new S controllers. People on Reddit talking about sending theirs in and getting another controller from MS with the same problem. So, i wonder if anyone has any ideas on how to fix it?