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.

something you can do to trouble shoot the wire is take a multimeter and your controller open up the controller hold one of the pins on the gcc port

make sure you are only in contact with one pin on the multimeter then on the circut board test each socket that the cable plugs into there should be 6 while testing each port you should hear 1 beep per gcc port socket if you hear to then you have some wires crossed if you dont hear 1 then you have a weak connection or cut cable