Thanks, BDMaster. To clarify: I did NOT flash anything. I tried to flash the unmodified biosreg. But this did not work because my original BIOS is still locked. My problem results from flaws in the original bios.

I need to figure out a way to enable legacy boot in the original bios settings (without breaking anything) before I can continue. This is because I understand that RU cannot be booted via UEFI. And without RU I cannot unlock my original bios.

I made some progress:

1.
I managed to boot RU. For this purpose, I only deleted the security variables in the original bios screen but did not enable Legacy OS boot. With normal UEFI boot, RU initially did not work/boot via USB stick. However, I attached a Lexar card reader, inserted a SDcard prepared with RU and then it booted.

2.
Within RU, I used ALT+C to find the bios variable PCHSetup and changed 0x1C from 0x01 to 0x00. Hopefully, this was the bios flashing lock.

3.
Booted to windows. With FPTW -bios -d biosregunlocked.bin I hopefully saved a dump of the now unlocked (but otherwise unmodified) bios. I save the dump on a SDCard as a backup.

4.
With fptw.exe -f biosregunlocked.bin -bios I flashed back the still unmodified (except for the flash unlock) bios. This worked! In other words, the bios was really unlocked and I did not get Error 167

5.
With fptw.exe -f biosregmod.bin -bios I flashed the modified bios that BDMaster prepared for me. Thank you again so much, BDMaster!

6.
This is how it looks now ...



7.
If I enable overclocking in Advanced / Overclock Performance Menu, XTU works. XTU is factory-installed on this laptop but undervolting was initially disabled. Thanks to the Bios Mod it now works. Hurra!

Wow , many thanks , this is a real Tutorial to show as example !
many thanks for your report friend ...
Regards

I have now installed the latest Gigabyte Bios FB7 which means all mods are gone and, moreover, the bios is "locked" again.

I am not entirely sure "where" to unlock the bios. Do I have to go to line 10 x16 and replace 01 with 00?



https://abload.de/img/comp_img_20211121_18324j49.jpg

Many thanks!