I would say it is more that random ebay-pulls are not very builder-friendly, but that is a different argument for a different time.

Did you plug in the 12v 4pin or 8pin power connector generally near the CPU socket?

I might also double check standoff positions on the motherboard tray to make sure there are no extras poking at the board from behind.

And do try to find a manual if the front panel header info is not shown on the PCB.

It is also sometimes helpful to have model numbers of parts you are playing with if you are going to be asking for help.