black screen,no backlight, connects to itunes.

After liquid damage.. cleaned logic board, replaced battery/lcd digitilizer.

however screen remains black with no sign of backlight either. I can sort of see slight blackness on the lcd logic board component but wouldn't have thought enough to prevent the screen to not be working plus I would still have the backlight on, and its component is fine. ive checked that its seated in properly into logic board etc.

I can connect to tunes and battery is charging etc, it will vibrate when using the mute button.

would this possibly have anything to do with proximity sensor issue, (on/off button stopped working before the liquid damage) or lcd/digitilizer faulty or logic board?

Thankyou for any feedback