Chosen Solution
I’ve already tried resetting NVRAM the systems screen stays purple. I connected to a external monitor and works perfectly. I’m not sure if it’s the LCD or the iDP (eDP) cable is bad. The computer was never dropped or the screen is cracked.
Any answer to your question would be pure guess as there’s no way to tell what’s wrong without tests. It maybe be the screen, the cable or even some component on the logic board. Plugging the Mac to an external screen just tells us the GPU is working fine, nothing else.
