Rughugger is right. Let me explain :
Some 360 lots come out with this option. PASTE. Yes, Flux, a paste that melts on soldering and retains heat. It depends in which factory it has been assembled, because still some of them reffuse to buy the more expensive thermic paste. So they use the cheaper crap, and it overheats, it gets sent to microsoft, they do NOT find the culprit factory, ka-plam. They are forced to send you a new one, or fix the broken one.