mid 2010 21.5" iMac Problems

[gavO852]

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]

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?

C