Chosen Solution
Time to pick your brains. I’ll try make it short and sweet. I have an iMac mid 2011, for the past couple of months it’s been struggling to turn on, now it’s completely dead. I’ve taken the screen for to check the LED lights. LED 1 lights up then goes off, then a couple seconds later it has a faint light then goes off and stays off.LED 2,3 & 4 are not lit up. I tried changing the PSU but the same thing happens, unless it was another dodgy PSU? But know there’s power going to the PSU as I can hear it, and get I nice shock when I touch it haha My next guess would be to change the logic board? Unless any of you guys know what it could be?
Its likely a shorted out GPU MXM board Sadly these are getting hard to find ;-{ You do need to stick with the original Apple part as it has custom firmware. While someone with deep skills could reprogram the GPU with the needed firmware its not easy without the proper tools and knowledge. iFixit appears to still have one! iMac Intel 21.5" EMC 2428 Radeon HD 6750M Graphics Card Here’s the guide to put it in iMac Intel 21.5" EMC 2428 GPU Card Replacement
