Proform Treadmill?

I have an older proform personal traner treadmill. I have not used it for a year, but tried to get back on it recently. As soon as I plugged it in, it took off. There was no key in the console, and I have triewd disconnecting the console completely, but it still takes off. Sparks shoot out from under the treadmill, and the circuit breaker blows.
Any ideals what needs to be fixed/replaced?