I have had a number of APC Back-UPS XS-1000 / XS-1200 UPS power
supplies failures over the last year or two. Without exception, the
problem occurs when I turn on the power switch at the back of the
computer. It seems the current inrush overwhelms the UPS and fries it.
So far about 5 or 6 of them have been toasted. The all-up wattage of
the computer (the only device attached to the UPS) is about 600 watts.
I do try to minimize using the main power switch.

To APC's credit, they have replaced them all so far, though the return
postage is starting to add-up.

I would appreciate any advice, perhaps in terms of something that
could mitigate the current inrush?