I have an ROG G750 and I had done ALL of the suggestions found online from update ATK, filters off, etc... I had a keyboard lockup as well with the backlight issue, typing response was delayed, and my touchpad would not function or toggle. So with this weird combination I tried updating my bios and the winflash told me I had to have 20% battery to do it. Well, if you have one of these laptops you will know the battery has charging issues, so I have had my permanently plugged in for awhile now. I caved and ordered a new battery so I could get the new bios updated and BOOM! ALL the problems were instantly solved. Keyboard delay went away, the backlight came back on and FN keys now work for them, and the touchpad toggle works. All because of a low battery. The batteries are "supposed" to last two years, but if did the ATK, BIOS, driver updates, and checked keyboard filters to off... then replace your battery. NOWHERE on the internet does it mention this solution, so wanted to be sure to post it here for anyone else.