With most UPSs, that's all that needs to happen. Someone with a bit of time on their hands and a few bucks can replace the battery and have a fully functional unit in no time. The batteries only last 2-3 years at the most and need to be replaced about that often.
There is probably nothing else wrong with the unit.
I have personally "refurbished" 3 UPS myself and they are now all in perfect working order. All I had to do was just replace the battery
My best find was a TrippLite 750W UPS (Watts, not VAC) that was sitting in the corner of an insurance company and they claimed that it never worked and wanted to get rid of it. They said that all I had to do was carry it out of the place and it was mine.
(Not an EASY task but manageable; unit weight 50+ lbs) All I had to do was plug it into the wall for 24 hours with no load and now it works great. I have my main rig, 19" monitor, pump, router, and dual DSLs running on it and it works great!!!!!
Hows that for knowing what to do...............