mid 2010 21.5" iMac Problems

May 7, 2018
Reaction score
I have this mid 2010 iMac 21.5” that I’m trying to fix. I put a new graphics card in it but that did not solve my issue. This iMac does not have a HDD installed and I made a Sierra restore usb. I plugged it in and booted to it on the iMac. I installed macOS on a 500gb External Drive to test the Mac. Once it finished installing, it booted from it and took me to the setup process. I got to set up a user account and the iMac just shutdown. I tried turning it on again and the progress bar got to 99% and as soon as it hits 100% it just shuts off. I can’t get it to boot to the OS. Can someone please help. ( Sorry for the long post )

EDIT: Also, I have to plug in an external monitor to see what’s happening. The internal display is not turning on and is treating the external as the primary display.


Cory Cooper

May 19, 2004
Reaction score
Hello and welcome.

As you are finding out, iMacs are not user-servicable, especially without the proper training, tools, and anti-static/safety precautions.

That said, it sounds like the issue wasn't the graphics card. It could be either the logic board, the LCD cable/panel, or a combination of multiple parts.

-How did you make the Sierra restore disk?
-Did you install it to a flash or hard drive?


Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.

Ask a Question