This tutorial shows how to fix the backlight issue in Acer Aspire 5336 notebooks.
When booting your Live CD/DVD add the following boot options to the grub menu :
Press enter to let the boot process continue.
When the screen turns black press the Fn key along with the brightness button.
Once installation is complete verify your grub configuration (/boot/grub2/grub.cfg) to see if the acpi options have been added. The grub entry should look like this:
If not, add them and update grub.
Now, to eliminate the need of pressing the fn combination we can add the following lines in the /etc/init.d/boot.local file:
while [ true ]; do sleep 1 sudo setpci -s 00:02:0 F4.B=0 done
Thus every time the system boots, the brightness setting will be triggered and backlight is switched on.