When a UPS no longer responds even to being plugged into the AC wall outlet what does that mean? What is my course of action? Do I take it to a technician to replace the battery?
Some UPS'es have the screw-in type of fuse, others have the fuse in a small pop-out box underneath the input socket. Unplug from the mains before checking the fuse!
Should the fuse be OK, then it might be something else. If you're not comfortable with opening it up (high voltages present inside!!!) then you can take it to a tehnician for repairs.
I have replaced UPS batteries as well, and you'll have to be extremely careful where you touch... Luckily I haven't been shocked yet.
Check fuse, then battery - you can get a replacement battery from most security shops - just take the old one in (power off, un-clip the red and black battery leads, take out battery) and ask them for the same spec. I changed the battery on my 1000va UPS a few weeks back and it cost about R140.
If you are not too sure on the UPS give Cyberdyne a call and see if they can help with fixing it.