Suggestions:

1. Get a voltmeter, check for voltage at the battery lead. If it's zero, you have an open circuit.

2. Also check the voltage from the charger. It should be over 4.8 volts.

A voltmeter is a good thing to have, even a cheap one will work.

Your charger is on, any time it's plugged in. The lights that indicate it is charging do not go out. If the light is not on, the charger is not connected to a battery.

Good luck,
Dave Olson