Backlight
check if X can set backlight
< Collapse code block
xbacklight -set 10
if it can, then inability to change backlight from keyboard or gui may be Scan Code or desktop environment problem.
Else creating /usr/share/X11/xorg.conf.d/20-intel.conf
file with following content has worked.
Section "Device" Identifier "card0" Driver "intel" Option "Backlight" "intel_backlight" BusID "PCI:0:2:0" EndSection