1. Make sure the battery is installed properly and has sufficient charge.
2. Please unplug the servo and then rebind the transimitter and truck, turn on the remote control first and then turn on the car, if the car is able to go forward and backward, then it can be judged that the servo is broken.
3. After step 2, if the car still can not go forward or backward, it maybe the problem of the ESC or transmitter.