In my laptop I seem to remember that the backlight have a separate power connection. Might be worth checking if that have come loose, if it's the same in your laptop?
Asus ROG G55VW:
CPU: i7 3630QM
GFX: Geforce GTX660M with 2GB ram
RAM: 2x8Gb 2133MHz Kingston HyperX Impact (surprisingly the G55VW uses the 2133 X.M.P. profile)
Storage: RAID0 with 2x 256Gb Crucial SSDs (both msata, one in a sata adapter)
OS: Windows 10 x64