A client's dead UPS took down five servers and my whole afternoon
Last Tuesday a faulty battery in a 3-year-old APC unit at a dental office in Tucson shut down their whole rack, and I spent 4 hours tracing the surge damage before realizing the UPS itself was the problem; has anyone else had a backup unit kill more hardware than it ever protected?
Have you checked the charging circuit on that APC before swapping the battery? I had nearly the same thing happen with a unit at a small law office last year. The battery swelled and the charging board went bad, which sent dirty voltage into everything downstream. Cost me a whole weekend to replace two switches and a NAS that the UPS was supposed to protect. My rule now is to test the output with a multimeter under load every six months, not just trust the "replace battery" light. Those lights only catch the battery, not the board that charges it, so the real killer hides until it is too late.