X Box 360 turns on but freezes on logo

I dont know what happened to it, maybe it overheated. Anyway, I have an Elite that used to work and now it just freezes when the big XBOX ball pops onto the screen. It happened a long time ago and i stopped using it for about a year. I decided to try it again and it worked for about a week. I had it up on risers so it had plenty of air flow so it wouldnt overheat and didnt have it on for more than 2 hours every time i used it. Any way to fix this or figure out whats wrong with it on my own?? Thanks!