iMac Black Screen; LED 1&2 lit, Fan spinning
I got an iMac 21.5 Late 2012 which is not turning on. Diagnosis LED 1&2 are on when I press the power button, fan is spinning, HDD too, but nothing else happens. I have already exchanged the CPU, still no luck, RAM is checked and working.
I now suspect the NVIDIA graphics chip to be broken as the 3rd LED is signaling the connection to the GPU.
Any comments/experience if this could be right? Any other suggestion to fix this?
so to close off this repair, I found out that the WiFi module was defective, I just replaced it and everything works fine again. So if you see the same failure on your iMac, just remove the WiFi module and see if the iMac is working again.