PC not booting :-(

I'm brand new to PC building and just created my first build, but it's not booting up properly (details below). Here are the parts:

CPU: Ryzen 5 3600 Motherboard: Aorus b450m RAM: 8g GPU: GTX 1650 3 fans Case: phantex eclipse p350x case PSU: 600w

The issue is that it does not turn on my monitor. The cpu cooler fan starts spinning and then stops. The motherboard troubleshooting indicator (red LED lights) show that it is a cpu problem.

It initially worked when I had a Gigabyte GA-A320M motherboard, but I wanted to have more than two fans and I did not know I could just buy a splitter. So I got a new motherboard that supported more than two fans.

Everytime I wanted to turn on my computer, I would have to turn off the computer and the power supply switch. I turned both back on and my monitor wouldn’t work and the CPU red led light was on. I repeated this process twice, sometimes three times, and then it would finally turn on and everything was running smoothly until I put it on sleep mode. Then my computer would go back, where the CPU led light is on and then I could no longer turn it on unless I turned off power and power supply multiple times. (PS. Whenever the cpu cooler stops spinning, the pc doesn’t work)

When it works, the CPU cooler fan spins continuously and the RGB turns colors.

My friend told me turning off the power supply switch every time was not normal so I began to look into it.

I tried installing more motherboard spacers, moving the RAM into different slots, and resetting CMOS. It didn’t work. I replaced the motherboard and cpu with the same model. It didn’t change anything. I double checked the wiring and took apart the whole thing. I thought it might be that the PSU can not support 4 fans, so I removed one and it worked. But once I shut it off and on again, the same problem occurred.

I’m just really confused and new at this. Any help would be appreciated. Thank you in advance.