DC doesn't see any of my controllers(please insert controller)

It keeps saying insert controller. What happened is one of my controllers had been damaged. the wires in the cord had been exposed, and I guess some of them touched each other. My Dreamcast was working fine until I pluged all four of my controllers in to play V-Tennis. Then It keeped saying insert controller. upon inspection I noticed the wires exposed on one of the controllers. I've tried different games, unpluging, I even opened my Dreamcast to see if I can see if anything was burnt. Looked fine to me. Anyone know what else I can try?