Chosen Solution
imac 21.5 mid 2011 I was instaling SSD drive into my mac and my LCD start flickering since than. I also replaced thermal paste on CPU and graphic card and add some more RAM during this upgrade. I tried to replace ram and cpu (I have a spare one) led driver board (doesnt help) and v sync cable (was damaged so I order new one- does not help at all). I also try to remove SSD and the problem is still here. On external monitor is everything just fine. I am not able to find any damaged part on my logic board or PSU. Everything else is working ok. https://youtu.be/SHNyUcMKYNY What do you think? Do I need a new LCD? Update (05/04/2017) New update. When it goes black I am still able to see desktop with flashlight. Update (05/04/2017) I perform apple hardware test with my flashlight and it gives me code 4SNS/1/40000001 : VGOR - 10.344 Does anybody knows what does it mean? Update (05/04/2017) Another hardware test. Code 4SNS/1/40000001 : VGOR - 10.382 Update (05/05/2017) New update. LCD completely stops flickering and when I turn on my imac it boots and after a few seconds it restarts itself very quickly and keep restarting again and again so i unplug whole LCD and now it works normally with external monitor. Does this mean my LCD is gone or maybe my power source? Update (05/05/2017) Now it is not able to start at all it just spins wents and shuts off.
when it flickers press f3 and it fixes the issue temporary.
