Question ASROCK B550m Pro 4, Back and Forth Between POST and No POST. What is the root cause?

Nov 29, 2020
The title is the TL;DR.

I built a system a few weeks ago and everything was working fine. I used it for a few days and was very excited with the results. No overclocking, I did a stress test. CPU was 64 degrees Celsius under 100% load. Very normal. One day, I boot it up and it does not post. The code on the Mobo says CPU. I have no way of verifying that without buying a new Mobo so I take it to a mom and pop shop (only place around where I live) because I read 9/10 times its the Mobo. The shop said they did not have the resources to test what is was, but they suspected it was a rare CPU failure because the Mobo seemed to be working.

I bought the CPU at a microcenter (just learned about that magical place). Where I am at, I had to drive over state lines to the nearest microcenter and now with COVID-19 restrictions, I am strongly advised not to leave the state lines. I saw that my parents have a microcenter near them in the state so I visit and help them out with their computer stuff. I drive to microcenter with my computer hoping to see about getting the CPU replaced. Lo and Behold, the darn things boots like nothing was wrong. Weird but Cool! So I take it home and use it for a week. Just now, I turn it on and no POST, Mobo light says CPU.

What is going on? If it were truly a CPU issue, I would imagine I would never get it to POST again, but they ran some tests at microcenter and said everything looks fine. I have not tried updating the BIOS because I am scared the power will go out. I am unlucky that way. I am hoping Santa brings me a UPS for Christmas to take away that fear but would updating the BIOS be the solution?

Thank you for your help in advance!

System Specs
CPU: Ryzen 5 3600
Cooler: Cooler Master 212 Evo RGB
Mobo: Asrock B550m Pro 4
Ram: Gskill 3200 8gb x 2
M.2: Crucial P1 500gb
GPU: EVGA 1050 (old I know, but it works)
Power Supply: EVGA 750w BQ semi-modular