1. Check the connection of the charger and the placement of the battery in the charger.
2. Unplug the charger from the power source and ensure both the charger and battery connection points are dry and free from debris, dust, or lint. Check also that there are no signs of rust around the connection points.
3. Unplug the charger and plug it into an outlet that is proven to be actively working.
4. Try charging a different battery.
5. If available, try using a different cable to connect the charger.