PS3 overheating when it isn't hot?

Boyfriend and I ordered a PS3 (fat) off ebay so I could play FFXIV Beta. First day I didn’t have any problems other than a slightly low internet connection signal but that wasn’t a huge deal. Loud fan, but loud fans are typical for the old PS3s. Second day, if I have the system on for 5 minutes, it will put up a message saying that it is going to overheat and I have to shut it off. Then another 30 seconds later, it cuts off on its own. The little light on the front never goes yellow. It first is green, then alternates between red and green, then when the system shuts off it just blinks red. This happens regardless of how long I wait in between having the system on and off. It doesn’t matter if I am playing a game or not either; it always lasts no longer than 5 minutes and gives the overheat message. The PS3 is blowing out warm air that is neither cold or really hot. My laptop and TV get 15x hotter than this system is getting :( I have filed a claim to get a refund, but is there something I can do for now or did I just get a busted system? (the seller had high ratings, claimed it to be tested and everything so I’m very upset)