Unable to update BIOS of notebook

[P_r1]

Good day, dear friends!

Problem: I am unable to update the BIOS of notebook. (Still have to use original version "F.14".)
1.  When I launch the official update programme and try to flash BIOS, it displays message looking like "Flash method is not supported...".

This situation repeats when I change between BIOS and UEFI modes and plug or unplug USB flash stick (formatted and with needed firmware files) to the notebook.
2.  When I reboot, the "F2" menu does not have an item "BIOS Management".

There is only a black screen with gray border and menu for diagnostics, not depending on presence of USB flash stick in system and files on stick.
3.  When I create the update USB flash stick with official update programme and try to boot .EFI (not sure about extension; I already tried to boot them all) files from it using UEFI manually, I only get error message about inability to boot on screen.

After that, log on the same folder of my USB flash stick also says that the boot was unsuccessful with some fatal error.

This situation repeats 3 years in a row with every new executable update package.

Please, help me.

Thanks in advance.

[KrazyToad]

@P_r1

Welcome to HP Support Community

I appreciate all your efforts and expertise in troubleshooting this issue

At this point I suggest you contact HP Support for further assistance

1) Click on this link - www.hp.com/contacthp/ 
2) Select your product type below.
3) Enter the serial of your device. 
4) Select the country from the drop-down. 
5) Select the chat or get phone number options based on your preferences. 
6) Fill the web-form and proceed further.

Thank you