If this was mine I'd remove the battery connections for cleaning and reconnection then go ahead and put the charger on it until the charger called the battery fully charged and try again.
If the battery is years old, the battery is taken to the usual Autozone for a test and possibly replacement.
Be sure to check both ends of the fat battery cable. I've found the other end corroded more than once.
An odd new problem has developed with my Jeep. Battery voltage shows 12.69 volts. When I turn the key to start it, the lights and chimes go out like normal but, it won't turn over (doesn't even click) and the lights and chimes stay off for several seconds after I release the key. I've tried jumping the solenoid terminals to bypass the ignition switch but, it does the same thing.