ProForm XP 680 stops after 2 seconds?

Everything else seems to work on the treadmill, the incline, the display. When I hit the start button to start the belt, it runs for 2 seconds then just shuts off. The display screen resets too. I have tried hitting the reset button and it still does the same thing.
someone told me to do this: Unhook the wires that lead to the motor and hook them up to an 18 volt battery and see if the treadmill runs. I did that and the treadmill did run. I lost the email address for this person so can not get any more info on what this test means. Does it mean the motor is bad now?? Any ideas on this??