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.
Make sure the Keyboard backlit option is enabled in the BIOS. With the computer powered off, press the power button. Immediately start pressing the F2 key once per second (if the computer boots into Windows, shut down the computer and try again).