Paintball Gun Problem... Please Help!!!?

My gun is a Spyder Rodeo, and I got it from a yard sale a while ago. But recently I went out to go play with some friends and I went to shoot my gun (with a full CO2 tank) it just kept shooting and would not stop until I took the tank out. It also didn't shoot any paint , if that helps add to the description. It also has a leak, which I taped up to try to mitigate the problem. I tried to take it apart but quickly realized that taking stuff apart was not my forte. Can someone tell me if this is fixable and how easily it can be fixed so I can know whether or not to just buy a new gun?