He may have been charging it at too high of a setting. It's always best to charge an ATV battery at the lowest setting that you have on your charger. If you wouldn't charging it at a high setting, then you must have a problem somewhere. Is the neutral light coming on? If the solenoid was clicking, it probably was on. You could have a shorted battery. Check the battery or replace with a known good one. Check your wires for any melted or burned places. If that doesn't fix the problem, check your solenoid and starter.Something crossed wires if the battery was hot.