I live in an area with frequent power outages. It's a limitation of the area I live in. If something happens near the entrance of our town, the whole town goes out. Needless to say, I have more than one UPS in the house to sustain the various electronics I run. Mostly, it's to support the VOIP phone service and the MythTV network in the house.
I own several of the Belkin F6C550VA-AVR UPSes and an APC 350VA Back-UPS ES. When the power goes out, all of them sing a horrid beeping chorus, usually in the early morning hours. At that hour, the family prefers to sleep it out and not be jarred awake to the noise. Also, I have to get up and silence them all. Worse, just before the battery is drained, they scream again and again, until finally dying. Use the software to silence them you say? Well, not all of them are attached to computers. Such is the case for the cordless phone and downstairs in the basement for the cable modem (also provides phone via VOIP) and the router.
I set out to kill the internal speaker. It was a little rough on the Belkin, but much easier on the APC:
First, take out the battery from the back of the unit. This is safer, plus the cover works as a place to put the screws.
Next, take out the two screws from the back.
Place the UPS on its side and use a flathead screwdriver to pop the plastic clip from the front cover off the bottom.
Now, put the UPS back upright and work the front cover off by lifting from the bottom up. Remove the two screws holding the left and right side of the UPS together.
Here comes the tricky part. Working the sides apart, remove the top panel (the part with the AC outlets). I popped the right side of the UPS off mostly, then pulled the top panel off the left side as it rested on the table.
See that little blue cylinder? That's what makes all the noise! I removed it by wedging a small flathead screwdriver under it. Working carefully in a circular motion, you can pop it right off the circuit board. Be careful not to crack the circuit board! Do the whole process backwards to put it back together. Now I can sleep!
This little APC was much easier:
First, flip it over, take off the battery cover and remove the battery. Then remove the five screws holding the back cover on.
Lift the back cover off and look for a little black cylinder. That's the speaker, but this one was a little harder to pry off the board because it was soldered closer to the board. I used a smaller flathead to be able to get under the speaker and I cracked it off in several tries. The picture below was taken after I removed the speaker, but you can still see the circle on the board where it used to be.