Windows 11 Z8 g4 impossible to get in BIOS/Firmware

[Alex2018]

  Hi,
    I have a Z8 G4 CTO with 3 GPUs and two screens, connected to the same GPU, four NVMe on two boards and another disk. USB keyboard and mouse, with Windows 11.
   After an update of Windows 11 sometime ago, it crashed, so I had to reinstall the computer from an USB, even the recovery option was not working, now, no matter what I do, it is impossible to access the BIOS, but I need to access it, to activate the virtualisation, that I need for something I plan to do with WSL and Hyper-V.
    Notice I had never tried to access the BIOS on this computer before having that problem, though to reinstall Windows 11 I had to use an USB stick, and that worked fine.

   The BIOS is at the latest version from august, even ran the BIOS update and confirmed that.
    The computer does not show the "press key to enter BIOS" standard message, I tried anyway to press F10 and ESC in differen tries, it just stay on with the disk access lit forever (well,  did not wait forever, but we are talking about ten minutes reading a book while waiting) with fans at full speed or almost, and shows nothing and does nothing.

  Had to power it off from the button, and put it back on.
   Made sure I had disabled the fast boot, same thing - Windows 11 is slow at boot, but honestly, it was already slow, did not see any noticeable difference, and I even have the doubt/impression it is slightly faster in getting to the logon window now that I disable the fast boot (?).

   Tried to  use the Windows 11 option to  reboot in recovery mode and get to the  UEFI firmware settings, same result.

   The only result of all these attempts was that when I tried to enter the computer after the last attempt, I had to reset my password, because I was putting the correct one (I checked showing it) but it was insisting it was wrong (?) - then I reset it to the same and it worked fine.

      I wonder if it could be a problem linked to the fact of having two screens and multiple GPUs, thus having to take hardware off to be able to get in the BIOS, or if I should try to take out all power included the CMOS battery and press the button power button for some time (basically, completely reset the BIOS), but before I go for something radical like those steps, I would like to know if somebody had a similar experience and some suggestion .

    I even have an old PS/2 keyboard I could connect to the computer, but I have another Z8 G4 where I used the same USB keyboards to access the BIOS without problems (although I think with only one screen connected), so I am sure it is not the USB keyboard itself.
  But I cannot use that instead, it has a less powerful CPU configuration, and I want to keep Windows 10 there as a backup option (it already saved me when Windows 11 crashed), given that Windows 11 has had more than once problems with updates, one this Summer screwed up the NVMe of someone I know, then MS admitted there was a problem.

    Thanks in advance !