dell 3521 la-9104p no backlight

[doctormasry]

hellolaptop dell 3521 la-9104p no light on screen
i can see data ok but no backlight
on jlvds
NV_PWR_SRC 18 v is ok
3vs is ok 3.3
lcdvdd is ok 3.3

i replacd led screen
and change flata ( caple between board and led )
any idea

[khaahk]

Voltages on:

pin36 INV_PWM
pin37 DISPOFF#