The Copperhead 10 has the sensor wire built into the ESC, so it's not replaceable...
@Rude1155 does the system just run on sensorless mode or does it not move/ functional at all?
I've never had any issues with mine, but if it persists, try contacting Castle Customer Support.
First, make sure it's plugged in correctly (right orientation, all the way in). If that's not it, it could also be that the motor wires are not plugged in the right order. What motor are you running?