Chosen Solution
Hi, Im having an interesting problem with my 20” iMac 2210. I bought the computer awhile ago off someone who told me that they took it to Apple and they said it had bad logic board. I ran some tests and had a pretty good idea that it was indeed a logic board issue. So I purchased an used logic board from iFixIt and installed it. I followed the guide word for word. All cables are attached to logic board and nothing is missing (except for bluetooth connector which doesn’t fit into this logic board for some reason. Maybe I was sent the wrong one). Anyways, I press the power button and fans/hd start spinning for about 5 seconds or so, then the computer shuts off and restarts by itself, at which point it runs forever. No chimes, black screen the whole time, and it doesn’t light up my wired keyboard and mouse. LCD and chimes happened on old logic board however. Diagnostic LEDs 1,2 and 3 turn on, but never the 4th. I understand the 4th means that the LCD isnt communicating. I have checked all LCD wires, they all appear good. And the LCD worked on the old logic board, however not on the new one. Can anyone help me out? This is so frustrating. TLDR: New logic board installed. Black screen, no chimes after hitting power button. LEDs 1,2 and 3 on not 4th. LCD screen worked on old logic board.
Put the old hard drive in an external enclosure . Hook it up to a Mac Runnin just Sierra, no higher. Repair the drive with Disk Utilities. Now see if you can boot from it.
