If your battery is not accepting a charge, first - remove the battery from the bicycle and try to charge it off of the bicycle. When you plug the charger into the wall, you should see a light illuminate on the top of the charger. When you connect it to the battery, one of these lights will turn from GREEN to RED. This indicates charging.
If you have no lights on your charger or the charger is too hot to touch, please Contact Us and we can do some additional diagnosis to determine the issue.