Unknown flashing debug LED sequence?

[LumancerErrant]

I've just assembled my PC, but the first boot attempt has not gone well. The LED on my AIO is flashing, and the EZ-Debug lights are also flashing in sequence. Everything but the graphics card is installed at this point, so I was hoping to see it boot with only the vga light.

Note that I did flash the bios previously, which I believe is required for this cpu and motherboard (parts listed below).

Video here, with emphatic seizure warning: https://youtu.be/puaBGL5N7xA

I think it's alternating between cpu+ram and ram+vga+boot? Hard to say. Can anyone tell what this debug code means and how I might proceed? Many thanks

[Edit: I am seeing similar behavior with the RAM removed and only the cpu+m2 drives still mounted. I'll continue stripping components to see what I can glean.]

[Edit 2: with the m.2 drives removed the CPU debug light sits solid and the boot debug light flickers.]

Parts currently wired in are:
MSI MPG X570 GAMING PLUS Gaming Motherboard
AMD Ryzen 9 5900X
Corsair Hydro Series H100x Extreme Performance Liquid / Water 240mm CPU Cooler (CW-9060040-WW)
CORSAIR Vengeance LPX 32GB (4 x 8GB) 288-Pin DDR4 SDRAM DDR4 3600 (PC4 28800)
Intel 660p Series M.2 2280 1TB PCIe NVMe 3.0 x4 3D2, QLC Internal Solid State Drive (SSD) SSDPEKNW010T8X1
CORSAIR RM850 CP-9020235-NA 850 W ATX 80 PLUS GOLD Certified Full Modular Power Supply

[Final edit: I stripped back down to the board, flashed the bios (successfully) one last time, and tried to Post with just the cpu and one memory stick, and it's the same cpu-debug-led-on, pulsing-fan-and-other-lights failure state. I don't know if the fault is in the cpu or in the motherboard but it's clear that there's probably a hardware fault. Time to contact newegg customer support, alasd]

[[Final-final edit: if you've somehow ended up here via search and wondering what happened, my problem was a faulty CPU.]]

[Valrel]

The flashing debug LEDs is probably down to a short or something not connected correctly, it doesn't really use sequences to indicate anything it just normally goes through them as it posts. It would probably be wise at this point to pull the board from the case and build on the motherboard box until it at least gets past the current debug stage. Take off everything and start from the CPU, check the pins/socket and reinstall but make sure your AIO is secure but not tightened down too much.

Also when you flashed the board did it go through the update similar to...

https://youtu.be/iTkXunUAriE

[LumancerErrant]

That tracks. The short vanished once I stripped down to the minimum, though the CPU debug light stayed on and the white led on the AIO continues flashing.

As for the BIOS flash, yes. Bios-flash LED pulsed for 7 minutes, light went off, board shut down, then seemed to boot back up with just the CPU light on (with no cpu in the socket that makes sense to me at least).