If your battery won't take a charge, check the following:
Check to see that your charger is connected properly to the vehicle charging port. Line up the notch in the charger plug with the notch in the charger port and plug into the charger port.
Charge for a full 8 hours. If the battery still has not charged, you may need to replace it. Use only genuine Razor replacement batteries.
If you have left the power switch on or your product has not been charged for a long period of time, the battery may reach a stage at which it will no longer hold a charge. These are lead acid batteries. The battery must be charged at least once a month when not being ridden or is stored during winter or the battery can loose the ability to accept or hold a charge even with proper care, a rechargeable battery does not last forever. Average battery life depends on use and conditions.