Chosen Solution
My MacBook began showing green vertical lines on various areas of the display. now the display black with pink lines across it. However, when i connect it to an external display. The image is fine and no lines are shown. Is it a GPU problem or is it the display? I tried resetting the PRAM and the SMC.. it made no difference.
Before you replace the LCD, try just reseating the cables. If it still does not work, try just slapping the back of the LCD a few times, it may move it back into place. Otherwise it would be a defective LCD. When it started, was there any recent drops, spills?
