Why won’t my pc post after I’ve tried everything?

My PC used to boot up, but now it won’t. All it will do is start, run for 30 seconds, and not post then boot loop and restart. I have to shut it off from the power supply to turn it off as the case button won’t. This happened with my original build, so I replaced the motherboard and cpu, thinking it was my old cpu since I had a bent pin on the last one. Yet, the problem persists. I bought a new motherboard that has argb unlike the old one, and my argb fans will flash when I turn the psu on and then never fully turn on. I’m suspecting RAM or PSU considering it won’t post. The PSU was used and bought from a friend working.

CPU: Ryzen 5 4500

Motherboard: Gigabyte B550 Eagle WIFI6

RAM: OLOY DDR4 RAM 16GB (2x8GB) 3000 MHz CL16 1.35V 288-Pin Desktop Gaming UDIMM (MD4U083016BJDA)

GPU: ASUS GTX 550 Ti(yes yes, I know it’s old, but it should be working as the pc problem persists even when I remove it)

PSU: Thermaltake Smart 650W 80+ Gold Non-modular power supply(it’s an older one)

Case(if needed): Corsair 3500X ARGB