No post on 2 sets of components

Hope I'm on the right subreddit.

Specs-

CPU: 9800x3d Mobo: NZXT N7 B650e RAM: 2x 32GB Trident Z5 Neo 6000 GPU: 5090 PSU: NZXT 1200W NVME: WD Black 4TB Cooler: Noctua NH-D15 G2

Running into a frustratingly weird issue. My PC fans went to max, it shut down, and then wouldn't boot. Motherboard showed red lights on CPU and RAM. Read that a BIOS flash could fix it, but it won't flash. Indicator stays solid green.

Thought the motherboard was fried. Went out and got an MSI X870e Tomahawk. Red light CPU and yellow light on RAM. Ok, so CPU is dead. Just picked up a fresh 9800x3d and tried it in my original system and got the same 2 red lights.

For good measure I swapped to an old 1200W PSU and still, the same issue.

I've tried one stick of RAM alternating both sticks. Nothing.

Where am I going wrong?

Help me Reddit gurus, you're my only hope.