The same thing happened to me. I'm still using two stealths (out of four). I haven't had the overheat thing but did get the tank almost at room temp when the heaters were set @ 80. I just unplugged it four 24 hrs then turn up and down the dial and it seemed to work ok for now. I'll call marineland soon and try getting replacements too. For now ebo-jager, fluval m, and tronic heaters have worked great for me. All of the stealths are just a little over a year in use.