New PC won't turn on

[MekoGamesTV]

So, I just build my computer 2 hours ago. and I was Hyped. When I pressed the power button I can see the back lights of my mother board blink. But it turns off and no fans run or anything.
Things I have done.
>Checked Every cable and Power plug
>Watched many Tutorials on Building a pc they all had the same.
My Mistakes
>Didnt have any thermal paste so I used the stock one.
>I only had a problem with the USB Pin **The one that is blue**
My Specs
Case : Phanteks PH-EC300PTG_BW Eclipse P300 Temp Glass steel
CPU : AMD ryzen 5 1600 processor with wraith spire cooler
Didn't use any thermal paste.
RAM: G.Skill TridentZ RBG 16GB (2x8gb)
Power Supply : Evga 500 b1 Bronze 500W Power Supply
Motherboard: MSI Gaming AMD Ryzen B2350 DDR4
2 TB Seagate HD
256 GB SSD Silicon Power
Graphics card. MSI Computer Video GCase : Phanteks PH-EC300PTG_BW Eclipse P300 Temp Glass steel

 

[Cycloid Torus]

That cooler usually comes with a thermal interface pad in place - if so, the first time you attach it, it does not need thermal past - however, you will need to remove this and replace it with thermal paste if you take it off at some point. There are very good non-conductive thermal pastes on the market at reasonable prices.

I think you may have the motherboard model wrong - is it a B350?

"a problem with the USB Pin **The one that is blue**" - uncertain what this means, please clarify.

In summary, you appear to have a 'No Post' condition - which can be caused by dozens of issues - mostly relating to power, I.e., loose connection, pin shifted connection, incorrect connection used with PSU (not all 6-pins and 8 pins are the same), etc. In 5-10% of the time, it is a component problem (infantile failure, damage in shipment, damage during installation, etc).

You need to follow a structured approach and keep detailed notes... I like using this:
https://www.computerhope.com/issues/ch000607.htm