Quote:
If it's not something simple like a fuse, then there's no way I can diagnose it. Of course, if it's an SMT fuse somewhere, I can definitely do that.

Not much computer equipment that has an external PSU has fuses inside. Best case is that you've fried some discrete component somewhere along the line and replacing that will bring it back to life. Worst case is if the 5V line was connected directly to a big ASIC of some kind and it's now let the magic smoke out.