OK, so I had a problem running down an error code on an old Best Technologies Fortress LI660 UPS. Code was “A 4” which turned out to be “Alarm” code 4. Just means I have a battery going bad. I think this UPS takes two 12V batteries.
I like this UPS, easy to read buttons, shows Voltage out and Line in and whether you are in a brownout condition.
Manual is here. best-power-fortress-li-user-manual
I found other Best UPS manuals here http://www.powerprosinc.com/user-manuals.html
Hope this helps someone else.