A blowtorch and a hydraulic press also might help flatten 'em out. Get 'em a little squishy and force 'em back into alignment. See, the problem is that you've lost rectangularity, so the electrons get all confused and hung up in the lumps and wrinkles, and they can't leave the battery.
.... and seriously, I'm batting somewhere under .500 with replacing UPS batteries, so I've entirely given up on the idea. At least half the time, there's also a problem somewhere in the other electrical gubbins that was either caused by or was the cause of the lead-acid batteries pooping out. Sometimes stuff like a popped capacitor or whatever smells pretty rank, sometimes there's no telling what happened. Most of the time, I just recycle the old UPS and pop for a new one. They seem to go around four years, about the same as lead-acid car batteries.
In your case, this is a pro-(ish) level rackmount piece of equipment, so a little bit of a gamble is worthwhile, and maybe the electrical bits are hopefully better quality than the stuff in consumer-grade desktop UPS units. And it looks like the display is working, which bodes well. Your odds are somewhat better than even that it will come back to life when proper (rectangular) batteries are in play.
sigmastek.com
www.replaceupsbattery.com
