New pc not booting up, but mobo leds are on.

Hey, so i just finished first time building my pc and everything was fine, when i plugged in the power supply to the outlet the mobo rgb light turned on. But when i press the power button it doesnt turn on.
The mini led + - cables are not connected
But the power switch cable is connected, followed by manual.
I dont know what to do
I9-9900k
Asus rog strix z390-e gaming
32 gigs ddr4 3000mhz royal tridentz
Rtx 2080 windforce
MasterLiquid ML240L
Intel 660p 1 tb
Crucial MX500 500 gb ssd
Evga 650 gold 80+

Can you get us a photo of where you plugged in the front IO cables to the mobo?

Turn the wire around and see if that works.

Build it outside of the case on a piece of cardboard to verify you aren't shorting it out anywhere.