SmartUPS 1000 showing battery disconnected

[BillP]

I arrived to the office this morning to find that my UPS was completely turned off along with everything that was connected to it.  I powered on the UPS, and it has the error "Battery Disconnected", yet it shows the battery level to be 100%.  I re-plugged the battery cartridge several times and still have the errors.  This unit has a management card, and when I login to the interface, it shows the same error, but also shows the battery charge at 100% and plenty of run time remaining.  I am also doing SNMP monitoring of this unit, and it shows everything as normal as well.  If I unplug the UPS from AC power, it immediately shuts off.

The battery that is installed is only 1.5 years old.  I am trying to determine if it genuinely is a problem with the battery, or the unit itself, before buying another battery.