No backlight, backlight 0

Hi, i have a LG G3 S (a.k.a. G3 Beat) with a backlight problem. The light is at 0 and won't light at all. I can see barely something with some led light trough the display. I tried to restore with hard reset, changed the lcd but nothing. I was searching for a service manual for schematic pcb where this backlight ic is located but without success. The model is D722. Thanks for reply me.