Question MSI X570 Ace fails to start during SEC boot phase on 3 month old build (code: 0d)

Feb 5, 2020
MSI meg x570 ace AM4 ATX
AMD Ryzen 7 3800x
EVGA GeForce RTX 2080 Super

Build completed ~3 months ago, shut down normal last night, this morning it won't boot up.

Power is on, lights are on, fans spin, but the mobo is showing a code of 0d and the "EZ Debug LED" is showing a red light for the CPU. I have not opened the case or made any hardware/BIOS level changes in months.

From what I see the error code is "Reserved for future AMI SEC error codes" according to the manual (physical and digital copy from MSI site have same info). Googling it has not been helpful and they all seem to be new builds that are failing. MSI MEG x570 Ace user guide

Here is what I've tried so far resulting in no change:
  • Switch RAM around
  • Cleared CMOS with the rear IO button
  • Remove RAM
    • Turns out post response I saw was using codes for a different MOBO so I think this was pointless
  • Checked power connections to MOBO, CPU, CPU cooler, and the connections at the PSU
  • Checked that the CPU cooler was running.
  • Updated BIOS using the "Flash BIOS" rear IO button (showed code 00 for about 10 minutes while button flashed then went back to 0d)
  • Re-seated the CPU + CPU cooler (cleaned and re-applied thermal paste)
Currently I'm trying to see if the red LED for CPU is a false flag. I can't find any info indicating whether the CPU is tested during the SEC boot phase. Amateur hunch has me leaning towards MOBO. I want to try powering on with no CPU to see if the code changes but I'm out of thermal paste so if there are other things to test I want to do those first. I have stuff on hand to attempt part swaps though the thermal paste is still a thing.

Any information is appreciated.