Chosen Solution
After leaving my Pro Controller charging for more than an Hour it will not turn on or charge. Holding down the Sync button also does not work
Needs a new battery it seems like. Very easy to replace, all you need is a pretty tiny Phillips head screwdriver. Screw off the screws on the bottom of the black grips, then those 4 screws on the inside. You should be able to pop the backplate off and have access to the battery.
