My APC UPS fried my power supply?

My very old APC UPS might have damaged my iMac!

It happened earlier today while I was working, when all of the sudden the UPS made a screeching noise and my iMac when out and so did the UPS.

Don't get me started about the fact that a computer connected to a UPS is supposed to be protected from surges, at this point I just want to focus on getting my iMac back on running.

I tried several tips on getting the iMac restarted to no avail, so I finally decided to open it up and test the 6pin connector using all pinout combinations on the power supply.

I verified that AC voltage was coming in but no DC voltage was coming out from it.

Now, based on these tests I would assume that a protection fuse went out on the power supply because I understand that it's common for a faulty power supply to at least output some voltages, although this is not always the rule.

Can anyone out there point me to where a safety fuse might be located and perhaps some diagrams to really test the output voltages?

Thanks in advance!