N56VZ: no LCD backlight, need ideas on repair

Hi!

tl;dr: Asus N56VZ, no LCD backlight, but the image is there (tested with a flashlight). Replacing the LCD cable or LCD itself did not help. Ideas? Thx.

Long story: First, there was a small tea spill on the keyboard. No liquid inside on the MB, but the letter S (where some water went) on the keyboard stopped working, so I got a new OEM keyboard assembly directly from asusparts.eu. I had to disassemble the whole body to replace the keyboard.
In a few months the laptop stopped turning on, so I had to disassemble. Apparently the LCD cable was not rooted correctly in the plastic cutouts and got damaged when closing. There was a short circuit between the LCD cable (apparently the backlight wires) and the ground on MB. The laptop was starting/working fine (with external screen) when the cable was removed.
Here is a photo of a place on the motherboard where the LCD was short-circuited. Not much damage, imho.

So I ordered a new OEM cable from asusparts and temporarily repaired this one while waiting: it helped, the backlight worked and it was all fine.
After the new cable arrived, I replaced it and from that moment I've never seen the backlight working (even with the old fixed cable). The laptop runs, so there is no short circuit now.
What I tried:

• Ordered a new OEM LCD, no luck
• Tried using the old (manually fixed) cable, no luck
• Tried reconnecting the cable several times (both sides), tried measuring some voltages on the LCD, no luck
• Pressing the backlight up and down buttons on the keyboard (with Fn)

The LCD is LP156WF1-TLB2 and the manufacturer spec is available here (pdf). I don't have an oscillograph to test the LCD, but what can I do with a Voltmeter?
Apparently, the LCD is not getting a 'VLED' signal to turn on the backlight. Am I right?

Anyone, any ideas on what else I can try to replace? Buying (and installing, huh) a new MB is the last resort.

Thanks a lot in advance!

 

It could be the driver chip / circuitry on the motherboard itself has gone, it's not shorted but the circuit is no longer closed.

 

Any chance I can force the backlight to stay always on? It seems like I just need to send a simple signal to turn it on. Any ideas how I can do that without a complex circuit? Worst case I can put a simple micro-controller inside and solder directly to the pins, but I will need tools or someone's help for such a solution.
Can someone please look at the LCD spec (link in the original post)?

 

What I actually saw once is when I was plugging the screen in and out (when the laptop was powered on), I saw a backlight flashing once, so I think I just need to force it to be on externally somehow. Any ideas?