By the way mine blew up because the charge circuit decided to let the battery win.
Fixing it?
No it was completely fubared - tracks had lifted off the board, charring, exploded MOSFETs. Bad smells. It's high energy stuff so I didn't both risking creating a fire hazard. I'll dig out a picture when I'm next on my desktop machine.
I don't know about UPSs. I see people using them, especially in corporate environments, because no one ever got fired for buying IBM. Yet when I hear the various experiences working with them, it seems they cause at least as much problems as they solve. If your systems go down due to a UPS failure when the actual electrical grid isn't having any problems, you're not making things better. If power to your system gets cut momentarily before the UPS kicks in and does its job, it's not a lot of use rebooting from battery power.
They're pretty good. We have terrible power in our offices. This is fixed by a fairly large APC 15kVA installation (four half racks worth). They do a wonderful job of power conditioning as well as the job of a UPS. They are always online so there is no lag at all. Even if the line voltage surges, drops off 20 times in under a second, they just carry on. We haven't had any explode although I sleep with one eye open.
However, the best UPS out there is .... the laptop! They all have built in UPSs that last a lot longer offline and get tested more often. Laptops and some IaaS kit (Amazon etc) that you don't have to give a shit about because it's not your problem is the best way to run an SME these days.
I've been involved in some big UPS deployments, some with diesel generator backup. They are always a pain in the posterior, they often under-deliver but there are applications where you just can't tolerate avoidable downtime. But yes, as soon as you introduce a UPS [system] you introduce something else that can itself fail despite the fact that it's supposed to be there to prevent failures.
I worked for a large company that didn't bother to test their generator regularly because the last two times they tested it, it had failed to start. I don't even know where to begin with that one