DCP 3939 gateway backup battery discrepancy

My service seems normal.  Battery LED on gateway glows steady.  However, battery status when logging in to 10.0.0.1 summary shows battery at 0% and details shows no battery installed.  I opened the battery access door on the gateway and removed the battery.  It appears normal.  Replaced it, LED once again glows steady yet info on 10.0.0.1 continues to show no battery installed.  How do I interpret this?  Previously, info on 10.0.0.1 has shown battery power consistently over 95%.   Thanks in advance for any guidance.