[suicideneil]

You mean you have the esc set up to run 2 lipos in parallel?
Were the wires from the battery to the esc hot too, or just the unused ones?

Either way, sounds like the connector was shorting against something metalic ( you should cover it with something if only using one input )- the battery and esc would both be getting pretty warm too if it was just overgearing, and the motor would be cooler generally...