Chain load Windows 10 bootloader with Grub

40_custom

#!/usr/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.

# location /etc/grub.d/40_custom
# when done, run sudo grub2-mkconfig -o /boot/grub2/grub.cfg && sudo grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg

menuentry "Windows 10" --class windows --class os {
   insmod part_gpt
   insmod fat
   set root='hd0,gpt2' # gpt2 is equivalent /dev/sda2
   search --no-floppy --set=root --fs-uuid $uuid-of-efi-partition # change the var here
   chainloader /EFI/Microsoft/bootmgfw.efi
}

Windows Live CD commands

bootrec.exe /Rebuildbcd
bootrec.exe /Fixmbr
bootrec.exe /Fixboot