Chosen Solution
Hi, I have an 2015 MacBook pro. It was never dropped or damaged. Recently the screen works only when another display is connected via HDMI. Otherwise main screen is black, white or multicolored. We’ve tried to change display, motherboard, display wire. Didn’t help. Could you suggest any solution. please
Try booting without the I/O board connected (via both the power cable or I/O cable). I have seen 1 MacBook Pro 13" 2015 before showing diagonal multicoloured stripes down the screen when it gets into an OS, but this turned out to be a CPU issue; I can only imagine it would be related to the I/O board in some way if you have tried a new screen and board already. Make sure you are testing it with known working parts, and leave as much unplugged as possible when testing, so you can eliminate other parts causing a problem.
