Yes, as you’ve found, using /GAN and stock BIOS you’ve erased your NVRAM, and serial, UUID, and LAN MAC ID probably too.
If you had a backup you could fix with AFU /GAN again, but this never ideal method to flash, only as last resort and NEVER on Intel CPU system since there is other much better/safer ways to flash
Same GUID’s probably used, but since you don’t have a full backup there’s no way to check and see, stock BIOS does not contain these kind of NVRAM entries.
You don’t have ANY backup, from any software, even from years ago?? If not, maybe I can find a dump from this same system, if not we may not be able to fix your backlight.
NVRAM is only sparsely included in a stock BIOS (one entire volume missing and other only 5% is in stock), all this kind of stuff is never in there.
Serial, UUID and LAC MAC ID we can fix, from stickers on your board probably, but UUID/Serial really only needed for RMA, but LAN MAC ID You need to fix for Ethernet.
Sometimes windows activation may be tied to serial, or you may have erased the stock key from BIOS too. Only time will tell on that, you can check windows updates, reboot and see if it stays activated.
I found three dumps at one site, ideally I may need to download them all, since often people program stock BIOS, dump it and call that a dump which it’s not, so may need to get all three to hopefully find a proper actual dump.
I can only download one file per day from this site, so may take a few days. I will also look at other places for a proper dump too. Got two today so far, one from the site w/ 3, and one from another site, none actual proper dumps 
So, over next two days I will get other two files from the one site, while I also look for other sources too.
For your serial, UUID, MAC etc. Remove the back casing and send me images of all stickers on front and back of the bottom casing, and then images of all stickers you can see on the board with the back removed.
Be sure to look on/around the memory slots too, and remove the memory, sometimes sticker is hidden on the memory slot itself and or under the memory sticks. I don’t need images of the memory or it’s stickers 