u check if your fan is a little dusty, or its loud, cuz then u gotta clean it, but if its the cpu, then u should say, it was broken when i got it, if u dont say it, they waont get it back, i did that with a camera that a really annoying girl broke cuz i was taking pics of her just ask for a new one, lol
just return it and say that i had i computer before, and am an expert so dont screw with me, and i just turned it on, and used cpuz, or watever, and it was really hot.THey should believe youu. By the way, dont trust me all the way cuz im a noob