Yup... it's going to die. It's overheating if it is the 'old' kind.
The older ones have two internal fans. The fans are very cheap and unreliable. When one of them dies, the ButtKicker overheats and stops working.
When you unplugged it, it cooled down enough to start working again. This is exactly what happened to mine, though it was a couple of years ago. I took it apart, removed the two fans and replaced them with high quality fans, then reassembled it. It's been working fine ever since.
By the way, if you keep overheating it, it will burn out completely. I've known others to burn out permanently after the first failure.
Their newer version is made differently, does not generate the same kind of heat, and has no fans.