Question New build randomly stopped POSTing after 1 week

Feb 22, 2020
System Specs:
ASUS Prime X570-P
AMD Ryzen 5 3600
Rosewill Photon 650W
Team T-Force Vulcan Z 16GB DDR4 RAM
Samsung EVO 970

Working on a new build recently, got everything up and running maybe two weeks ago? Didn't seem to have any issues whatsoever. Everything seemed to work fine out of the box. No driver issues that I could tell, no problems on initial power on, was always able to push BIOS over to reading a USB drive and install Windows instantly.

Over the course of a week to 10 days, installed and played several games, had everything under load and didn't see any overheating issues. I did not mess with any overclocking or tinker trying to squeeze more performance out of hardware, was literally using everything w/ out of the box settings. So today I was watching a Youtube video, left the room, and came back in to the system apparently booting and currently at press DEL to enter BIOS screen... weird? Figured Windows rudely pushed an update that I failed to delay, no super red flags yet. Then it never loads windows and starts booting again. Gets to windows, goes black screen, and starts going to BIOS again. At this point, I'm concerned, and manage to actually enter BIOS. Nothing was running hot, everything looked fine. I got past a Windows log on one more time, turned itself off, and has been basically dead since. All that happened in less than 5 minutes. It not posting or even getting to the enter BIOS screen, so, doesn't seem like a Windows issue.

Another known but suspected innocuous issue: The PSU doesn't have the extra 4 pin power adapter for the board. Per prior readings if you weren't running a bunch of extra on the board this didn't seem like it would be an issue and considering I'm literally just using a GPU and an NVME drive and have nothing else plugged in, It certainly didn't seem like one when the system was running just fine for ~2 weeks under load before it committed seppuku during a Youtube video.

What it currently does/context:
-Spins fans and turns on lights, the mobo fan spins up, goes idle, then starts spinning again if let on for a while
-Once turned on once, the RGB power to my keyboard is never disabled even on shutdown so long as the PSU isn't turned off (which seems odd to me)
-The video card isn't hitting its RGB pattern, so it's deifnitely not somehow getting to Windows without having
-No beep code is presented, and despite the manual implying there could be boot codes I don't remember ever hearing the PC beep.

Things I've tried:
-Unplugging all peripherals, secondary devices, etc.
-Re-seating all the power cords as well as the GPU and RAM
-Going down to 1 stick of RAM and 0 sticks of RAM to see if I could at least induce a different error
-Trying all HDMI out and displayport outs on both the GPU and the board itself (including against multiple monitors)
-Removing the hard drive
-Pulling the battery and letting the CMOS for 30+ minutes and seeing if a reset helps
-Changing to a direct, verified wall outlet instead of a surge protector
-Removing the GPU just to test other behavior even though I wouldn't have visuals... I've literally had it down to just PSU / Mobo / Processor / Case and seem to get the exact same behavior regardless of what I do.

Any other thoughts on things I could do to resolve this or anyone that's experienced similar challenges? I currently have an expensive, RGB-enabled space heater and it's quite frustrating.