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That is so rare a problem, that I cannot imagine what caused it.
I refer specifically to the belt 'flipping over'. It must have been either
A. defective to an unusual degree, and/or
B. much too loose.
By now it is almost certainly defective. But aside from that the stress of 'flipping over' and blowing the circuit breaker, may have damaged more than one component in the treadmill, I'm sorry to say. That's just the sound of it.
However: are you sure you have adjusted the belt back in place, with the right tightness setting? it was obviously wrong before, but is it obviously right, now?
Also, does the belt show signs of damage? (probably. But if so, to what extent?)