Asus X55U Black Screen but work perfect on external display

[cosmin_purcarea]

Hi,

I have a problem with my notebook, I open the notebook to change the thermal paste, after this operation my notebook display is black. When i connect notebook to external display everything is work fine. I change that LVSD display cable is the same. On the notebook display I see brightness and the brightness can be change from that FN keys. Any ideas what can be?
Here is a short movie with my notebook display: https/sendvid.com/omjkvn01#

Motherboard is Asus X55U Rev: 1.4

 

[Laptop_Nerd]

Hi,

It's working on an external display and it's safe to say that it's not your graphics card. 2 things that you might to consider replacing or checking. First is the ribbon or cable connecting the LCD and the motherboard. Second is the actual LCD display might have gone bad and needs replacement.

 

[cosmin_purcarea]

Thank you, this is my problem i don't know from where is this, i want to replace but I don;t know what i need to replace, motherboard or the display.