Chosen Solution
Hi There. I have a problem a back screen issue. The fans turns on with the hdd and DVD drive. I checked the onboard diagnostics and LED 2, 3 and 4 are off. I have replaced the PSU but but still a black screen. I have replaced the cmos battery but still black screen. I have baked the gpu but still black screen. Ask for any info about Imac. Edit. I forgot to mention I plugged in a different keyboard when it was working and when 15 min past it crashed and I could turn it on but it would crash less then 10 min in it would crash. The next day it would not turn on I have the issue now. Update (01/08/2023) @danj
This is the gpu Update (01/08/2023)
The specs
Sounds to me Like A Scary failed logic Board Or CPU!Take it The board out and look for any corrosion,And Check The CPU Guide: iMac Intel 21.5" EMC 2428 Logic Board Replacement iMac Intel 21.5" EMC 2428 CPU Replacement
