I have Windows 8 and Kali Linux installed. While i was installing Kali there's an opportunity to install grub and i did it. But i am unable to boot Kali Linux and even see grub menu as far as there's the only boot option in boot menu i.e: windows boot manager so windows starts without grub. I tried to fix it by reinstalling and updating grub using post grub-install : command not found instructions. Grub was successfully reinstalled and updated, recognized both windows and Kali(as there're listed in grub.cfg) but i can't fix booting problem.
I am facing the same problem on kali-win 10 dual boot. The root of the problem seems to be Windows Boot Manager which excludes the grub EFI partition on your drive while booting.
Link to my question: Kali Linux is Installed but not showing in boot manager
One Solution can be to install the os on Legacy Boot option.