I called for the 3rd time last night (was on hold for 45 minutes!). They agreed and said that since there is a 1-year warranty, they would send me another battery. I guess I have to figure out how to install it myself - shouldn't be too tough I suppose.
Nonetheless, I got real lucky. I had been hearing that beep for about a week, and did not realize where it came from until I was in the garage doing some cleaning when I heard the beep again. I think it beeps once every hour. the lucky part was that had I not realized it until after the 30th, then I would have been out of the warranty period.
If a VZ technician is reading this, it would be nice if the ONT box could at least send a message to either the STB or the customer's e-mail notifying them that the battery needs to be replaced. I'm sure there could be a simple diagnostic check through the router's settings. Or perhaps having the box beep a little more frequently.
You've got to be very careful if you don't know where you're going, because you might not get there. --Yogi Berra