There seems to be an infinite number of fixes post on the web about reinstalling the ATK package. This is fine for those that had a single installation failure. But for those that had a motherboard change or a bad bios flash, that "fix" wont work. I found one that does and its ASUS's fault, it seems. See it appears that when you download the lastest bios form asus they are missing a block that controls this. So heres the fix I found and in 30 seconds my lights worked perfectly again.
To start things off, we'd like to thank @jcd69 who is a Volter here on our forum for his finds and tests related to this specific KB lights fix.
Critical: Please take note that this has only been tested on G752VL and N552VX notebooks (Aptio 5 FW).
This can happen after reconstructing a full 8MB BIOS image and programming it back or from something even as simple as a BIOS update. The KB lights suddenly stopped working! So how do you know which steps to take to remedy this situation? Find out in our guide below.
Most ROG Notebooks will go through a KB light sequence at POST where it flashes the lights on and off momentarily. If this happens with yours KB lights at POST, then this guide is not for you. If it's just in Windows when the KB lights do not work, simply reinstall the ATK drivers again (go to the ASUS support page specific to your model - download ATK drivers).
Note: This guide is for the absolute rare occurrence that no other fix has worked. So if you do not see the KB lights turn on during POST, and you have checked all flex cable connections several times over from the notebook disassembly/reassembly since programming, then it means that there was possible data corruption in the Non Critical Block 2 of the BIOS image; resetting NVRAM does not fix the issue unfortunately (tested).
So how do we correct this? As you may or may not know, the Gary Key fix has worked almost every time in regards to this problem. So you may wish to try his tool out by downloading it here and following the instructions inside first. If the same problem persists afterwards, you will want to try the following steps below in our guide as a last resort.
Note: In order for the KB lights to work again at this point if nothing else has, you need to have at least made a backup 6MB BIOS image when the KB lights did work. If you didn't, do not worry, just ask around the forum for someone to dump their 6MB BIOS image so you can use it to complete the steps in the guide; model of notebook does not matter here but the manufacturer does; ASUS Notebooks with keyboard backlighting only.
GUIDE on specific KB lights fix
Tools: AFUWIN v3.05.04
Prestep. Download and extract AFUWIN and locate a working KB light 6MB BIOS image as mentioned above.
Step 1. Run AFUWIN (AFUWINGUI) and go to "Open" and locate the working KB light 6MB BIOS image.
Step 2. On the Setup tab of AFUWIN, check only these boxes: Do Not Check ROM ID and Non Critical Block 2. Then click on "Flash".
Step 3. Once the process has completed successfully, simply close AFUWIN and restart your system.
Final. Smile at your working KB lights again!
Dreamonic, Mar 11, 2017