troubleshooting a DC MOTO controller

I recently purchased a 20" front hub e-bike conversion kit and built it up on an inexpensive folding bike. The kit consisted of a 750 watt wheel , throttle control only, brake levers , and controller. I road this bike for all of two miles and the wheel started to drag then would not respond at all to power input from the throttle. Even more strange to me, I disconnected the battery and the wheel still would drag UNTIL I pulled the connector cable from the controller. So the wheel will spin freely as long as the controller is not connected battery or not. Has anyone experienced this? Battery voltage tested at 41 volts so I don't think the battery is the issue and I do not have another controller to check if that is the problem. Any input would be greatly appreciated. Keep in mind this was a hobby kit. I do have much nicer mid drive bikes but would still like to get to the bottom of this one.

Controller: DC MOTO CONTROLLER BY LITHIUM BATTERY
Voltage: 36VDC
Current: 26amp

NWebiker said:

I road this bike for all of two miles and the wheel started to drag then would not respond at all to power input from the throttle. Even more strange to me, I disconnected the battery and the wheel still would drag UNTIL I pulled the connector cable from the controller. So the wheel will spin freely as long as the controller is not connected battery or not.

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That usually means FETs are blown (shorted) in the controller.

http://ebikes.ca has a Learn tab with Troubleshooting that indicates how to test the FETs, if you want to repair the controller, but it's probably cheaper and easier to get a new controller.