Answer to "GameCube Controller not responding got it two days ago"Are any of the wires inside the wire casing broken? This tends to happen to second-hand controllers, especially if the wires where wrapped around the controller to tight during storage.
Answer to "My PS4 Controller is dead"If the DS4 no longer responds with the PS4 then more than likely it's broadcasting a normal Bluetooth signal. To remedy this, I suggest cracking the controller open and replacing the USB board/ribbon cable. And to answer another persons question as to why you'd just buy the motherboard, the motherboard at $38 is actually cheaper than a new controller, which costs about $65-70 each.