Early 2008 iMac Power Supply Repair Help

Hey guys! This will be a long post, so just bear with me. I'm an experienced PC / Electronic tinkerer, and I recently picked up a 24’ 2008 iMac for $20 on Facebook. It doesn't turn on, so I took it apart to check the Debug LED's, which non of them lit up. So I began removing the power supply and testing it.

I'm not good with a multimeter, just the basics, however I tested the caps and the fuse and they all check for continuity. The 2 giant caps only tested in one direction, not both.

Anyways, i hooked up the iMac to power and used the multimeter to test for a 12v single, and im not sure what I did, but I popped the fuse checking around with the multimeter (heard it pop and no longer has continuity)

I know I will have to replace that fuse, but what / how should I test other components? Is the logic board bad? Can I get some advice here? I would order a new PSU, but I'm not paying $60 for one.