when press power switch light on the motor flashes but motor no go

when press power switch light on the motor flashes but motor no go

when i press the red power button, the green light on the top of the motor housing flashes slowly but the motor does not turn. when the max button is activated, the green light on that button flashes at the same speed as the green light on the motor housing, but stillthe motor does not turn. have replaced the battery to no avail.