The letters "OC" will always flash on the Scooter's display when it first turns on. If this code goes away after a couple of seconds and the scooter remains on and functioning then there is no reason for concern.
If the scooter flashes "OC" and then immediately turns off or if the display flashes an "O" or "OC" and has an unresponsive throttle then there may be damaged on the hall sensor or hall sensor wire of the scooter's motor. This issue will also commonly cause the front motor to 'lock up' so it cannot spin freely. This type of damage is best fixed by replacing the front motor.