New x470 Taichi won't post

Bit of a long story here.

I'm essentially rebuilding my PC. Components are as follows:

Motherboard: ASRock X470 Taichi Ultimate
CPU: RYZEN 5 3600
GPU: Sapphire Radeon Pulse RX 5500 XT
Memory: G.SKILL Ripjaws V Series 16GB (2 x 8GB)
PSU: Antec NeoECO 620W
Storage: Samsung 860 QVO 1TB Solid State Drive
Case: NZXT H510

I put these pieces together, powered the thing on, and... the machine powered up, the LEDs started a slow pulse, but the screen stayed dark. After a moment of the fans whirring, the machine powered off, only to power itself back on again. This continued indefinitely until I turned off the power myself and messaged some friends.

The sharp-eyed among you will have noticed what I came to learn: the x470 needs a BIOS update before it can deal with the Ryzen 3000 series. Rather than wait for the process to get a boot kit from AMD, I opted to just buy a cheap older CPU from Newegg. A few days later I installed an AMD Athlon 3000G and tried to start it up... only to have the same cycle, except this time the LED numbers at the bottom of the board gave me what appeared to be a 61 error code.

From what I've read that's a chipset initialization error, so I pulled the CMOS battery, waited for an hour, replaced it and hit reset, to no change. So far, what I've tried:

-CMOS reset button
-CMOS physical battery removal
-reseating all power cables and data cables
-removing one RAM stick and reseating a single stick in each of the four slots
-removing both RAM sticks
-Reseating GPU
-Removing GPU (tried to cover every single base imaginable here)

My IT friends were at a loss. They decided that it had to be a defect with the motherboard, and the only available option left was to replace it. But something is nagging at me. Am I missing something?

The Athlon 3000g requires an even newer BIOS version than your R5 3600. The Athlon
came out a few months after the 3600, the behavior is different because the
Athlon is based on an older architecture but still requires a newer BIOS to work.

https://www.asrock.com/mb/AMD/X470%20Taichi%20Ultimate/index.asp#CPU

If you are looking for a fast way to update without a boot kit, always get a CPU
that is supported on all BIOS revisions for your board.

All the 1000 series AFs are new too, if you look at the compatibility list I linked
you will see the 1600(YD1600BBM6IAF) requires BIOS version 3.9, the 1200 AF is
even newer than that.

AMD has really confused things with this AF situation. They are essentially 2000
series parts rebranded as 1000 series parts. Your best bet would be a non AF
1000 series or something like a 200ge.

You can also identify what BIOS your board shipped with by looking for the
white sticker on the BIOS chip, it will have a version number printed on it.

I am seeing issues like yours a lot lately, with AF parts being so cheap many
people are tempted to go with them and end up with the same issue.

datonyb wrote: *mumbles quietly asrock dropped the ball by not providing bios usb flashback on the taichi high end boards*

The x570 Taichi has BIOS Flashback, it only took 2 generations
At least ASRock listen, eventually

I am having the same no post issue with a Taichi X470. I have tried 3 CPUs that should work with any bios and all of them get the post code 00. With a 3700X installed I don't even get a post code. Needless to say I am RMAing the board. I am very frustrated and disappointed.