Last night, my G15 keyboard backlight stopped working suddenly, I couldn't find a fix anywhere, so I decided to make a post in case it happens to anyone else. 

I did a couple of things in an attempt to fix it, but I'm not exactly sure what worked. 

Firstly I tried enabling it from the BIOS (spam F2 on startup to get into the BIOS), but that didn't work.

Secondly, I tried running down the battery to see if it'd fix it, but it's almost impossible to kill it completely.

Lastly, this is what I think fixed the problem. I powered the laptop down by holding down the power button until it shut down, and then I powered it up and booted into the BIOS. I changed the Keyboard illumination(in the advanced tab) from "Disabled" to "Bright", changed the times from 1min to 5mins, and saved & exit from the BIOS. When my laptop was booting back up, I immediately went back into the BIOS(by spamming F2) to confirm my changes had not been reset, and that solved the problem.

Hope this post saves someone the stress.