Please post your system info as outlined here:
Also please post the output of the following:
ls /sys/class/backlight/
Now replace < result > in the next command with the output of the previous command:
ls /sys/class/backlight/< result >
Please post your system info as outlined here:
Also please post the output of the following:
ls /sys/class/backlight/
Now replace < result > in the next command with the output of the previous command:
ls /sys/class/backlight/< result >