Chosen Solution
Hello, iMac (Retina 5K, 27-inch, Late 2015) doesn’t power on at all. Completely dead. No sound, no lights, no fan or drive noise, black screen. All four hardware diagnostic lights are off. Could the power supply or logic board be damaged? Need assistance trying to figure out what’s wrong. Thanks for any feedback.
Before trying anything else, plug in another electrical device into the wall socket you are using for the computer, just to make sure it’s not a problem with the wall outlet/fuse. If the other device works using the same outlet, it sounds to me like a power supply problem. (I’m pretty new to repairs, so don’t take my words for 100%) iMac Intel 27" Retina 5K Display Power Supply Replacement
