Asus S46CB screen video cable or motherboard problem?

[Fsa Assault]

Hello there, I have the Asus s46cb laptop, I had a problem with the keyboard (some buttons not working) so I decided to disassemble it and some cleaning.
After assembling it again,I got black screen, I plugged in D-Sub monitor, the laptop is working fine and I was on Windows.
I have another laptop which is the Dell Inspiron N5110, I attached the screen of the Dell to the Asus video cable and motherboard, I got white screen.
I attached the Asus screen to the Dell video cable and motherboard, it worked.
I can't switch cables because both of them has different motherboard socket, so I can't make sure if it's a cable problem or motherboard problem.
I want to buy a new screen video cable for my Asus, but I can't decide which model is it.
any advice would be much appreciated.
sorry for the long post

 

[Fsa Assault]

Here's an update, I bought a new video cable for my Asus screen, and I'm still having the same problem.
So is it motherboard issue for sure now ?