MacBook Pro Display Issue Diagnosis - Please Help

Hi All,

I have a macbook pro retina that is has a unique LCD issue. When you turn it on it shows a distorted apple logo as shown in the picture. (Looked like a graphics issue to me).

However when you plug it into an external display the laptop works perfectly with no problems at all.

I am trying to figure out what I need to replace. Obviously best case scenario would be that it is just a faulty cable:

Cost of a new display: $400

Cost of a LCD cable: $25

Before I go buying anything I thought I would come and ask if anyone seen this type of distortion before and if so, what was the cause/solution.

Any input would be appreciated.

Cheers

Matt

extra picture: