Macbook pro 13 Mid-2014 Black screen, but external works

Hi,

I've seen this problem around here before but cannot really find the answer to this problem. And by answer I mean: send in to apple and spend a lot of $$$ to fix it.

My Macbook pro will turn on, chime, and just give me a black screen (WITH backlight on). When connecting an external monitor I can see the Apple logo on boot, but it will freeze after loading 60%.

When booting into safemode with external monitor, everything seems to work find (except horrible performance). Original screen is still black.

No error when running hardware diagnostics.

I did everything recommended (included a reinstall of OS) to no avail.

So what is causing this problem?

Why is my mac only working with external monitor in safemode?

If this only was a bad display cable, the external monitor would work just fine. (I tried to reseat the cable on the logic board)