i solved the previous issue using a live cd instead of the usb memory flash..
so i correctly installed the OS but unfortunately now i have another issue. when i choose to boot with ubuntu from the grub screen, i get stuck with these error codes:
in this thread i found this solution
[8.417978] [drm] nouveau 0000:02:00.0: DCB I2C entry invalid
[8.516004] [drm] nouveau 0000:02:00.0: PRAMIN flush timeout
[12,455571] [drm] nouveau 0000:02:00.0: PRAMIN flush timeout
[16.328490] [drm] nouveau 0000:02:00.0: PRAMIN flush timeout
but i can't figure out how to make it work.. i tried to modify the boot option with grub, but it doesn't boot yet..
After completing the installer, Ubuntu still wouldn't boot- in recovery mode, I'd see a "pramin flush timeout" error message, which was related to problems with the builtin nouveau nvidia driver. By adding "nouveau.noaccel=1 blacklist=vga16fb" to the kernel boot options, I was able to get past that error and boot, then fix the problem permanently by installing the proprietary nvidia driver