Check whether the start button wire connector is dropped, whether the start button is damaged, check whether the start button is energized, and measure the resistance value with a multimeter (the pointer of the multimeter can't move, it means normal).
If the motor is missing, check whether the three-phase power is normal.
There is another type of rocker cutting machine which is equipped with a thermal relay. Check whether the thermal relay protection is tripped out. If it is pressed and then restarted, please replace the thermal relay.