Question Just built a pc and it won’t turn on

[Ineedhelpsendhelpplz]

My pc turned on once, then I turned it off through the power button, then it didn’t turn back on again. This was before I had any cables to the monitor and I didn’t have my gpu. I can confirm the front panel connectors are put in right, and the power cord works, because there is a green light on the motherboard when I turn on the psu.

The pc doesn’t turn on when I short it. What did I do?

 

[Dark Lord of Tech]

Specs would help us help you?

 

[Ineedhelpsendhelpplz]

Intel Xeon X5450
Thermaltake cL 0497
Asus p5g41c-m lx
Neo Forza DDR3 1333mhz ram
500gb 7.2krpm WD hdd
Sapphire (not Amd) radeon he 7850 2gb
Apevia Venus 450w “Atx” psu
Rosewill fbm x1
3.0 to 2.0 adapter
Fan connector splitter adapter
Sata to 6 pin adapter
$184 total

ALSO I got the pc to turn on after taking everything apart and putting it back together, but not it won’t turn on again