You've established that the pedal assist isn't working at all now. Leave that for a moment. Next question. Can you even ride this bike under power using the throttle? Your answer isn't clear. You said the wheel will spin with no load (wheel off ground) while you hold throttle. Will it spin using the throttle while riding? If the bike runs and then stops, but will restart after a reset of the power switch, the battery is probably defective. Means it can't handle a load. If you can ride the bike with throttle, go back to that wheel off the ground test. Spin the pedals backwards and see if the motor runs. If it does, they put the disk on backwards.