Enable brightness control=1

sudo nano /etc/rc.local

echo xx > /sys/class/backlight/acpi_video0/brightness

cat /sys/class/backlight/acpi_video0/max_brightness

Section "Device"
        Identifier  "card0"
        Driver      "intel"
        Option      "Backlight"  "intel_backlight"
        BusID       "PCI:0:2:0"

EndSection

Section "Device"
    Identifier "Intel Graphics"
    Driver "intel"
    Option "AccelMethod" "sna"
    Option "Backlight" "intel_backlight" # use your backlight that works here
    BusID "PCI:0:2:0"
EndSection

xrandr --output LVDS-0 --brightness 0.5

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"