I have a 2001 Yamaha Warrior, and I'm having some problems with the battery. The quad was running fine a few days ago, but after I finished riding, I accidentally left the key turned on. The quad sat for two or three days with the key turned on, and now the quad won't start. Thinking that the battery was dead, I pulled it out and tried to charge it on my Stanley battery charger. The problem is that when I try to charge the battery, the charger is showing that the battery is fully charged and will not charge it any more. I know that there is nothing wrong with the charger itself because I just used it for my other quad battery and it worked perfectly. I am able to use jumper cables to start the Warrior, ride it fine, but it won't start back up with the electric starter after I turn it off. Is the battery just bad or could there be something else wrong with the quad itself? Thanks