[PLUG] UPS is beeping sporadically

[John Jason Jordan]

For the past several days my APC Smart UPS, model SUA1500, has suddenly
started beeping at random times. If I ignore it the beeping stops after
a minute or so. Once it stopped when I gave it a smart slap on the top
of the case, although this remedy worked only once. It appears to hold
a charge fine, although I don't know how to test it to be sure. While
beeping none of the trouble lights on the front panel come on. When the
beeping first starts the green charge indicator lights are all lit, but
as it continues to beep they go down, as though the charge was rapidly
depleting. 

I suspect that some electronic device inside is going out, although it
could be the batteries. I've had it for about two years, but I bought
it used. I think it is going to take someone with proper equipment to
troubleshoot, and it may just have to be replaced. Does anyone have any
suggestions for local places I can take it to for diagnosis and/or
service?