I changed the motherboard, which subsequently changed the bios and the whole system. My backlight stopped working and I tried everything to get it working again.
I had W10, I had W8.1. I tried all drivers combination, everything and nothing worked.
Then one day I check on the net and find this video and it helped me! My f3 and f4 are switched and it doesnt work exactly as it did before but I still have 3 stages of lights and everything is back to working condition!https://www.youtube.com/watch?v=Wd33Z3PpUdQ
Hope this video helps you too!
Asus Rog G750JZ
Screen: 1920x1080 17.3'
CPU: Intel® Core™ i7-4700HQ (3.4Ghz @ -70mV)
GPU: GeForce GTX 880M 4GB (OC +125Mhz Core, +600Mhz Memory @ 1.062V)
RAM: Samsung 32GB 1600MHz
Storage #1: Samsung Evo 840 250GB
Storage #2: Samsung Evo 850 500GB
Storage #3: Seagate Barracuda 2TB
Storage #4: Samsung Evo 128GB MicroSD