Why Isn't my unit turning on? The unit comes with a safety feature, where the unit will not turn on if the battery is not inserted correctly. Related articles The battery is charged but the unit isn't turning on. My mower is not starting up. What are some potential issues? What if I need to service my Sun Joe Mow Joe Lawn Mower? Is the battery fully charged? What if I need to service my Sun Joe Mow Joe Lawn Mower?