Any ideas to resolve this? (Read desc)

Hey y'all, I just got a used computer from my grandpa and I go to plug it in and see the BOOT, VGA, and DRAM diagnostic lights pop up. I've attempted reseating the CPU, testing multiple DIMM slots and modules, using and not using the GPU, resetting BIOS and CMOS, but nothing works, so currently suspecting a bad motherboard but coming to you guys in case I can save a little money. This PC worked perfectly fine for my grandpa before he upgraded to a better system and gave me this one, only after transport to my house and assembly is when this occurred

Here are the specs:

Motherboard: MSI MPG X570 Gaming Plus

CPU: Ryzen 9 5900x

GPU: Gigabyte Vision 3080

RAM: 4x 8gb-4000 T-Force Sticks

PSU: MSI MAG A1000GL PCIE5

No storage but tested with an M.2 drive and nothing happened.

Also, the diagnostics lights turn on immediately after turning on PSU, put not the PC itself? Not sure if that's normal or not. And when power button pressed, nothing occurs, fans don't spin or anything.

Anything helps, whether that's telling me the cause of the problem, or I'm completely cooked and the PCs bricked, I appreciate it all. If you need more information let me know.

I've also recently tested the power supply and cables using the paperclip method, and they function normally.