@majk3l Hi and welcome to Win-Raid forums.
The reason you can’t flash the modified file is because a single bit in the BIOS has been set telling Q-flash to check if the file has been modified.
You can change this bit using a hex editor.
There is a post here that describes how to disable the check.
Alternatively you can use the modified version of EFIflash in this thread to flash it from a bootable USB stick.