Dead Battery

My inverter did not charge batteries when batteries reached 49 Volts, which was setting in program 12 on inverter. First battery from inverter was completely dead, and 2nd battery was at 8% charge. I then set program 12 on inverter to 50 Volts, and 2nd battery started to charge. But 1st battery from inverter remained off and not charging. I have a fully 100% charged 2nd battery from inverter, while first battery is dead. I have turned on and off the breaker and on button many times. I have also pressed the reset button for over 10 seconds many times, and still have a dead 1st battery. What do I need to do for inverter to start charging 1st battery?