At this point to be troubleshooting:
① Unplug the brake lever (normally open brake). If the motor is running, the brake is broken, the brake should be replaced.
② turn the source 5V voltage normal, check the turn signal voltage, turn the handle, the signal voltage should be 0.8 ~ 4.2V from low to high changes. If the voltage does not change and less than 1V, then turn the handle or turn the line short circuit. If the voltage is greater than 1V and the change is normal, detect the motor Hall signal (yellow, green, blue line). If the three-phase Hall signal line voltage is all 5V and the contact is good, then the motor Hall is damaged, should replace the motor or motor Hall element.