Linuxcnc installation

First of all Hello to everyone . 
i am a newbie and just trying to install linuxcnc and it stuck at GRUB installation failed and i can't figure out any way to continue the installatiom . Can someone please help ?

Disable secure boot in BIOS.

Hello Tommylight, secure boot is already diabled but im still stuck .
Can no internet be the problem as during installation process pc is not connnected to wifi?
I will try an ethernet cable , hopefully it works.

Should be ok with no internet.
See if there is UEFI and Legacy in bios, set it to Legacy.
Also see if there is CMS and try enabling it.

  The system installation is finished but without bootloader . It says i have to boot manually and i tried every available option but nothing helped to boot the system . The last option i tried is to keep the stick in pc and boot live system and since last 40 minutes its stuck on a blinky underscore "_"

None of those will work.
Missing GRUB can be booted manually using a floppy or CD or USB, it can also be installed after failure, but none of those are simple nor easy.
It is much easier to reinstall.

What program did you burn the USB stick with?
My old standby win32diskimager does not work with later hardware.
I moved to rufus which worked
More recently I have been using Balena Etcher which is fast and reliable

I would also disable network install in your Bios. It could be that you do not have Grub installed because of this setting.

Hello rodw, i used rufus to burn the USB.
I cannot try anyother program to burn the USB because i cant acces any operating system . Linux is stuck and windows is flashed . I can try disabling the Network install, hopefully it works.

You must connect to the Internet during installation