The first thing to try would be to get the brightness keys on your keyboard to work. Have you tried the acpi_backlight=vendor kernel parameter? Here is how:
1. Edit the grub file:
2. Change the line that reads:
sudo leafpad /etc/default/grub
3. Save the file.
4. Update the boot loader:
5. Reboot your computer and try again to see if the brightness keys work.
If not, I have a script that can automate the brightness changing, but it will need to be modified to your setup. Can you run the following command and post back the results:
^^This command will report back your backlight interfaces and their current values.
for interface in /sys/class/backlight/*; do echo $interface; cat $interface/max_brightness; cat $interface/actual_brightness; done