Flashing yellow light and intermittent audible alert

2002 Gem E825. When plugging in charger, it does not start charging. Yellow light flashes on dash with an audible alert.
All batteries have been charged individually. Charger was working fine before. Left for a month and level was down to 60%, so disconnected all batteries and charged them with an external charger. What does this alert mean. Can find no answers in the manual. Thanks

Look at the charger itself for error code. Might be mis-connection if you disconnected batteries.
I never bother to unhook wires to charge. Doesn’t hurt to open disconnect though.