PC won't boot

A few days ago, my replacement motherboard finally arrived from the repair shop after they had to swap out a faulty BIOS chip under warranty.
Once the board showed up, I couldn't actually test anything because I was still waiting on my RAM and GPU to arrive. As soon as everything landed, I put the build together and hit the power button, but there’s no signal to the monitor. The case just shows a solid green light and all the fans start spinning. I'm honestly not even sure if it's posting, since it's been so long since I used this rig that I can't even remember what the startup beep is supposed to sound like... 😁 It should have worked fine, though, given how it ran before. I'm starting to wonder about the power supply—I've got a 460W Linkword unit, but the official specs for my HD 6850 say it recommends at least 500W. I also suspect the PSU might be the culprit because the light on the DVD drive doesn't come on, and the tray won't even eject when I press the button. Plus, neither my keyboard nor my mouse are lighting up, and there's zero sound coming from the tower.
Let me know if I missed any details.
Thanks in advance for any help...
I'll probably drop it off at a local repair shop in a couple of days to let the pros take a look, but I wanted to see if you guys had any thoughts first.

You hit the nail on the head there, shadowlynx102. Just because the fans are spinning doesn't mean everything is fine. If you've got the power cable hooked up to the DVD drive but the tray won't pop open and there's no light when you boot the PC, it’s a clear sign that the component isn't getting any juice. It's not an issue of your power supply being underpowered, either; it sounds like the unit just kicked the bucket.

Honestly, I’m inclined to agree with you—it sounds like a faulty power supply or one that’s just completely kicked the bucket. Before you go dropping cash on a new unit, do yourself a favor and try to borrow a spare from a friend to test it out first. It might save you a headache if it turns out to be something else entirely.

So, does it mean the dog can kick the bucket even if the PSU fan is spinning along with all the other component fans?
I'm just really hoping it wasn't some other part that fried...