Traxter 500 power issue

I have a 2000 Bombardiar Traxter 500 and while I was riding on the trial it quit on me and had no electrical power. I checked the battery terminals and they were loose so I tightened them and was able to start it. I rode a little bid more and it did it again. I pulled the battery and checked the cells and the battery was completely dry. I put jumper cables from another ATV directly to the positive and negative cables on my ATV and it started right up. I got a new battery which has a charge to it and when I installed it I still have no electrical power. Does anyone have any ideas on what I can check to research the problem?