grub not installed

[beli_ven99]

so ,recently i installed kali linux latest version on my laptop lenevo ideapad 320

when i was about to complete installation i faced a problem it said ''installing grub dummy failed'' .and then i continue without bootloader

it said like that..
" you will need to boot manullay with the /vmlinuz kernel on partion /dev/sda2 and root=/dev/sda2 quiet passed as kernel argument."

and from then i am booting manually every time .I tried running boot -repair disc , it said "locked NVram detected "
help me guys i am new to community!!
i also tried this...

sudo grub-install /dev/sda
[sudo] password for kali:
Installing for x86_64-efi platform.
grub-install: warning: Cannot set EFI variable Boot0004.
grub-install: warning: efivarfs_set_variable: writing to fd 6 failed: Interrupted system call.
grub-install: warning: efivarfs_set_variable: failed to unlink /sys/firmware/efi/efivars/Boot0004-8be4df61-93ca-11d2-aa0d-00e098032b8c: Invalid argument.
grub-install: warning: _efi_set_variable_mode: ops->set_variable() failed: Interrupted system call.
grub-install: error: failed to register the EFI boot entry: Interrupted system call.

[TarantulaV1]

Hi Beli! Is this solved?
I'm facing another issue... Just recently I installed Kali Linux on my MSI GE62, with GRUB so I could jump from W10 to KL, but no idea why but my W10 does not start up anymore...
Just thinking about to start from scratch again, but not sure if you know a way to check what happened and maybe reinstall windows from KL?
I'm also new to the community, so maybe we can catch up and help us out together with the issues we have :)

Thanks!