I’d like to thank all the people, who wrote manual on this forum.
And people from 4pda.ru for instructions of using CH341a programmer
I could not flash BIOS via software. I think BIOS is hardly locked after load, so I had to use CH341a programmer with Quad SPI mod.
Here are files for programmer - the original BIOS ROM, dumped from my mobo before flashing, and ROM with “big” NVMe module included.
P8H77VLEorig.zip (4.3 MB)
P8H77VLEwNVMe.zip (4.3 MB)