Chosen Solution
I have a GameCube that I haven’t played in awhile. It powers on, plays the disk fine, but won’t respond to any buttons that I push. I have two wired controllers that don’t seem to work in any of the ports. There is never any error messages. Is this a problem with the controllers or with the console ports?
Are they the original GameCube controllers, or third party? Either way, to have both not working does not bode well for the ports. If you can find a controller that is known to work on another GameCube, plug it in and see what happens. If it fails, you know it’s the ports. If not, it’s just bad luck with two controllers that died at the same time.