Speed Passion Problems

[Callum]

Hiya chaps,
Was running my b4.1 for about 4mins during a lunch break at my local track everything was running fine, once finishing using the car I put it on the bench still plugged in and whilst chatting to a mate smoke started pouring out the back of the motor I quickly unplugged the battery and the positive wire was red hot as well as the motor and speedo.
Now the motor will not work it's burnt out for definite but just wondering what caused this?
Also I plugged the motor into someone else's car to make sure it wasn't the speedo and now his speedo will not work at all!
Any ideas??
Many thanks Callum
P.S it's a Reventon Pro