I charged my Sansa over night as usual then unplugged it from my computer and put it in my brief case.  A couple hours later I pulled it out and noticed it felt very warm,  especially the lower right hand corner on the back.  I tried to turn it on and nothing would happen.  I don't have mu documentation with me.  Whats the best way to contact tech support? 

I got it as a Christmas present so I don't think I have a receipt.  Suggestions?