Cannot get in BIOS settings

[CoreNS]

Hi! After converting SSD disk from MBR to GPT and starting to use UEFI mode (previously was in Legacy), cannot enter BIOS anymore. Esc. ,F2, F10 do not work, also getting to UEFI via Recovery from Windows environment does not work. The PC works fine. System information confirms Prodesk runs in UEFI. Just want to know how to enter BIOS in case of necessity later. The only solution I found is resetting CMOS which is too complicated to do every time. 

[itsmyname]

Power-off your computer.

Hold-down any key on your keyboard.

While holding it down, power-on your computer.

Do you see a message like "keyboard error. Press <some_key_is_listed_here> to enter BIOS SETUP" ?

[CoreNS]

I tried it twice with different keys. Unfortunately blank screen and then PC goes straight into Windows without chance to get into BIOS.

[itsmyname]

With the computer powered-off, and not connected to electrical power, disconnect the "power" or "data" cables from the disk-drive.. Reconnect the electrical power cord to the computer, and start the computer. Since the computer cannot connect to the disk-drive, to load Windows, you will get an error-message, and an opportunity to press a key to enter BIOS SETUP.

[CoreNS]

This task is same complexity comparing to simply pushing BIOS reset button on motherboard. I was wondering if this Prodesk 600 G1 behaviour is normal (not being able to access BIOS) after switching to UEFI and secure boot on.  Or is something wrong in BIOS settings? The only BIOS change as far as I recall, after setting defaults was to turn secure boot on and legacy mode off.