Display backlight failed after liquid damage.

This MacBook had water spilled over the keyboard. The original owner turned it off and placed the laptop in silica gel beads. After a week in the beads, she tried turning the MacBook on but the screen had no backlight. After a closer examination, the motherboard has no noticeable damage or corrosion, in fact the laptop looks fine from the inside. The only damage I found was one of the connectors going to the screen was burnt. The main connector to the motherboard looks fine. I am wondering if the motherboard may not be damaged and it was just the screen that failed. If anyone has knowledge on where I can test to see if the backlight circuits are working, that would be greatly appreciated. Due to not being able to give a definitive diagnosis, the original owner recycled the MacBook with us and bought a replacement MacBook of the same model from us.