Restore power button to default behaviour I have LG G2 (D801) on Android 5.0.2 Lollipop, rooted. The power button stopped working. I am pretty sure an app messed up its behavior - I don't know which one of the many I recently un/installed trying to fix another issue. I am pretty sure it's not a hardware issue. 

How could I restore its default behavior: press to optionally lock the screen and long press to bring up the power menu?
Just go full stock with a factory flash. See if the problem is present then. If it is, it is a hardware issue, and you can claim warranty. If it works, be a lot more careful with your apps next time.