Thanks for your quick response!
Based on the files from my link, can you tell me whether the system will still boot after flashing a modified BIOS? I have read in other posts that the Boot Guard cannot be bypassed, and I want to avoid the system no longer being able to start.
What surprises me, however, is that no colored markings (e.g. yellow or red) are displayed in UEFITool NE for the regions and that a full backup with FPT (green message: Operation Successful) is possible.
I will definitely make a backup with the USB-Programmer before attempting anything else.
I still have to read the other post ([Problem] Lenovo ThinkStation P3 Ultra Type 30HB - BIOS Update Failure - #76 by earthoo7) in full, but as far as I understand, the flash did not work here either.