The instructions in OP are actually very precise, but I have tried to summarize it a bit here (NO guaranties, if you mess up, this wll with HIGH propability BRICK your phone)


Assuming you have download original firmware 20.2011.40-4 (using Navifirm for example) and named it firmware.bin
Assuming also you have download openmode kernel and renamed it openkernel
Assuming you have downloaded Nokia flasher v3.12.1

Put all the files in SAME directory

1) turn off your N9
2) unplug your N9 from the usb
3)from command line run: flasher -F firmware.bin -f
4)plug in your phone via usb
when one command finishes {it will say 'Success'},
5) run: flasher -F firmware.bin -k openkernel --flash-only=kernel -f -R