AsRock x570 Phantom Gaming ITX/TB3 mATX, Graphics on Board using a Ryzen 5 5600G or Similar.
Very Important. No panic. Contact support both at AMD and AsRock. In my case I needed a Ryzen 3 3200G to complete Bios Update. Direct flashing from Bios and a Bios file in a USB FlashDrive won't work. Read further.
Board would only go into a Boot Loop with a black Screen. No Post Screen nothing. Before I went and spent money on new CPUs, Transport costs, etc, I contacted AMD Europe who kindly sent me an Emergency CPU, a Ryzen 3 3200G, to be able to Update the Bios. Then AsRock Support in Europe sent me some instrutions to Update the Bios properly.
The Bios has two sections. An Upper and a Lower. With Direct Flashing using a file read from a Flash Drive using the bios Bios itself and using the Ryzen 3 3200G, only the Upper section was being Updated. A common problem with Boards which now support Ryzen 5 5600G but before did not!
To update the whole Bios one has to create a Bootable Flash Drive with some Files one has to Download from AsRock. The files are based on a Shell with a Prompt Command line. We also get a scrypt file to load the Bios File and instructions even on how to ammend this file to accomodate the correct or desired Bios version.
AMD and AsRock every helpfull and open. They will gladly help. Without them I would have had difficulties, although if we read properly through the Bios Update pages at AsRock we can find the solution for the problem.
They are experts at support and very quickly we get through the Update.
After successfull update with the 3200G I rebooted and changed the Bios to Default parameters. Switched completely off, including Power Supply. Then reisntalled the Ryzen 5 5600G. Rebooted and waited a few minutes. Patience is important here. It might not reboot straight away. Switch off and Reboot again. Then I had the Bios working and installed the New OS. Thank you AMD and Thank you AsRock for the solutions.
Do not panic just contact Support. Good Luck.