The scooter is producing a "1" or other flash codes just after placing battery pack on scooter.

For scooters with removable battery packs, the key must be removed from the scooter while putting the battery pack on the scooter or removing it. This is to ensure that the scooter is completely powered down. 

Placing or removing the battery pack on the scooter while the scooter key is in the 'on' position will nearly always generate a malfunction code and the scooter will not operate. Should you inadvertently put the battery pack on the scooter while the key is in the 'on' position, you can clear the malfunction code and restore the scooter to proper operation by turning the key off, waiting for five seconds and turning it back on.