Hi Tom, do you have the brake lever switches connected? If so, unplug both of them and see if it then runs.
Do the three LEDs light up on the throttle unit?
Have you made 100% sure that no wires are exposed and touching each other on the horn/lighting feed and pedelec/reverse wires?
If you have a pedelec connector fitted, you can check that the +5V feed is still working by measuring the voltage between the red and black wires on the motor pedelec/reverse cable. (If there is no 5V supply from the controller, then the motor will not run.)
Check that none of the connector pins have been bent or damaged.
Is there an error code displayed on the BAC-601 display unit?
If there is no error code displayed, and no obvious connector problem, then it could possibly be either the controller or a Hall sensor problem, but you would need to remove the wheel and controller to access the Hall sensor wires to check their operation with a voltmeter.
Alan