BR1500G random beeping

[Anonymous user]

I have a 5yo 1500g that started beeping oddly yesterday.  It's hosting a plasma TV, cable modem, router, sound bar and clock. Load is 3/5 on the meter.  Power in our area isn't great but it's not coinciding with power loss.

At random times when loaded it'll do a long 3-4 second beep then stop. Nothing new or different displays on the lcd. It's not making a click or humming noise like the unit typically does when switching to backup, just the beep.  Once or twice it made a very sick beep like it's trying to cut off before it ends.  When no electronics on just passive draw it'll make a single very quick Beep instead of the long one. Again random times. Sometimes it's 30 min apart otherwise several hours.

The issue is its a new problem and nothing has changed in the past year that we've been in this house. No battery replacement light or faults. Yes the sound is turned off and still shows that on the lcd.  Any thoughts?