Question Motherboard faulty? CPU faulty?

[Zacharoni Macaroni]

This is my first build so I might be doing something very wrong here, but I think there's either something wrong with my CPU or my mobo. I built (or tried to build) my first PC about 3-4 days ago and I've been trying to troubleshoot since. I built it on the first night and it would boot up for a few seconds, then shut down, the CPU light on my mobo's debugger was on, so I kept trying to figure out the problem, thinking it was the CPU. I reseated it, made sure there were no bent pins, re-applied thermal paste, reseated ram. I took out my hard drive and GPU, and it booted up. I plugged in hard drive, still on, then I shut it down and put the GPU back in. Booted up fine, I go to the bathroom, come back, and my PC's off. Now, it won't even boot, I press the power button and it turned on for maybe half a second, LEDs lit up, then shut right down. There should really theoretically be no way that the computer is prevented from booting up unless something is broken, I thought it was the CPU, but that doesn't make sense, because it shouldn't be overheating or anything. Please help, I'm desperate, system spec below.
Specs:
CPU: Ryzen 3 2200G
GPU: Nvidia Geforce GTX 1050
PSU: 700w Apevia supply
RAM: 1x 8gb stick, 3000mhz
MB: MSI b450m gaming plus
(Not that it matters) hard drive: 500gb
Case has 2 fans at the front if that makes a difference

 

[Calvin7]

Power supply has an extremely short warranty. That indicates low quality. You might want to try another. if you are still under the warranty period you may be able RMA it for an exchange.

• Warranty
• Limited Warranty period (parts): 1 year
• Limited Warranty period (labor): 1 year

 

[DSzymborski]

Yeah, Apevias are shockingly poor quality PSUs. It's hard to say if the PSU is causing this problem, but it's difficult to diagnose anything while a junk PSU is in the mix.

 

[Zacharoni Macaroni]

Power supply has an extremely short warranty. That indicates low quality. You might want to try another. if you are still under the warranty period you may be able RMA it for an exchange.

• Warranty
• Limited Warranty period (parts): 1 year
• Limited Warranty period (labor): 1 year

Ok, unfortunately my return windows for Amazon closed 2 days ago. Kind of a bummer, but thanks for the help!