On Feb 4, 9:26 pm, wrote:
The UPS units are APC Back-UPS XS-1000 and XS-1200 models which I
believe are rated in-excess of the 500 watts of the PSU.

Your 500 watt supply, like most desktop computers, probably never
draws anywhere near to those 500 watts - with or without inrush
current limiting. Those UPSes should supply something like 500 and
700 watts continuous - even higher during short and sudden current
demands (also called a power surge). Numbers suggest damage is not
due to excessive load.

Numerous AC problems can exist including brownouts, noise, and
harmonics. Excessive harmonics can 'stress' some equipment. Is your
problem based in excessive harmonics? (Harmonics can be created by
other devices on AC electric such as 'ceilings' of fluorescant
lights). Harmonics can cause some equipment to consume more power;
create more heat. IOW harmonics can damage electronics even if UPS
was not providing a load. UPS should not be damaged by excessive
harmonics. Should ...

Were UPSes fixed by replacing failed batteries? Just another
speculation.

Problem: no provided facts explain your damage. At best, we can
only speculate. Known numbers imply that damage did not happen. Your
situation is a failure where facts to explain that failure are
missing.