Solved Black Screen Has Blue Lines On Boot Up That Actually Move Around Imac Intel 27 Retina 5K Display

Chosen Solution

Pic below shows black screen on boot up, very quickly, then blue lines fade in and out, and eventually disappear, moving track pad brings them back, then disappear etc… No fan, no noise except initial mac boot sound… Any ideas?

So you never see a viable desktop correct? If that’s the case your display assembly is damaged. On the backside of the assembly is a circuit board (T-CON). If you look at Steps 5&6 in the iMac Intel 27" Retina 5K Display Teardown you can see what I’m talking about. What can happen is in the process of taking the display off you can damage the ribbon cables leading to the display. Sadly its time for a new display assembly Ouch!