For anyone else who is having this problem, here is an answer I found here:
Open a terminal and type in the terminal:
This will open rc.local file. Now at the bottom make sure it looks like below and save.
You should be fine, reboot and check it out.
sudo setpci -s 00:02.0 F4.B=00
My system's backlight comes back on fine during boot up with this modification. There's also a really helpful script for switching the backlight back on when you 'wake up' from suspend or hibernate