Finally got around to trying to change the UPS battery downstairs yesterday. I Googled the APC model # and found what was supposed to be a compatible battery and got it at a local Batteries Plus for around $36 and change with a coupon. I go behind the TV to do the swap, unplug everything, turn the UPS upside down, open the battery compartment, and then discover that the "battery" is actually TWO battery packs joined together by a cable. (No way could I remember that after 5 years.) I only have one battery pack but don't really care because I only need 10 seconds of power before the generator kicks in. I decide I need more room and can't work behind the TV, so I cut the electric plug loose from the cable ties that the TV installers used. I go to lift it up and underestimate the weight; it tips over and puts a small dent in the wall. I get it out to the counter, remove the double battery, install the single battery, plug it in, and try to turn it on. Nothing. It's completely dead. No power. (Yes, I believe I connected the leads properly and reversed them and tried again just to make sure.) I don't know if it's because it fell or because it only had one battery pack that it wasn't working, but I couldn't take it anymore. I rush out to Best Buy and get a CyberPower UPS on sale for $130 plus tax that has almost the same wattage rating (805 watts, I think) as the APC UPS that I had before and that they're now selling for $210. The only big difference is that the CyberPower UPS has only 4 UPS-surge plugs (and 4 surge-only), while the APC had 6 UPS-surge and 2 surge-only, but since I only use the UPS for the HR24, DVD burner, and Xbox, that was fine. Both have similar digital displays on the front. I come home, plug everything into it, plug it in the wall, and everything is fine now, except for the small dent in the wall that's hard to see but that I know is there.
Morale of the story: don't cut corners and try to take the cheap way out. Every "simple" job I try to do ends up being a major headache.