Hello, good job for this topic, really useful. In my case, i'm off on the step 7... the last. I use an Asus G55VW and we have to set manually in BIOS the path for booting.
Basically, we have 2 HD (sda and sdb) and the BIOS see only the EFI partition on sda (created by vendor/microsoft).
After executing your topic, I have 2 choices (between the EFI partition on sda and sdb), however, my partition EFI on sdb is empty. I created /EFI/Boot/ and paste Bootx64.efi + grub.cfg and set the BIOS path on /EFI/Boot, /EFI/Boot/Bootx64.efi and finally /EFI/Boot/grub.cfg but nothing worked.
Any idead ? Thanks a lot
