Back-UPS XS 1000 Beeping Once Every Two Seconds, All Lights Flashing

[BillP]

Hi everyone, I just got back from vacation, and noticed the following

• Beeping once every two seconds
• On Line light on continuously (as expected)
• On Battery, Overload, and Replace Battery lights flashing twice per second

Here's what I've tried so far:

• Unplugged everything from the unit
• Shut down the UPS, unplugged it, and disconnected the battery, the put everything back together
• If I leave the battery disconnected, when I plug the unit back in and power it on, the On Line and Replace Battery lights illuminate solid, and there is no beeping
• Voltage coming from the battery pack connector is 13.7 (I measured both terminals, they're identical)

On one hand, the fact that the unit performs as expected with the battery pack disconnected indicates a chance that the issue could be the battery pack, on the other hand, the battery voltage is measuring as correct, and the unit is not performing as I'd expect it if the battery pack were bad.

Appreciate any advice you guys might have.

Thanks,

Ricky