Imac won't fully boot

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Imac won't fully boot

Imac (mid 2011) is stuck in the endless boot cycle but will not fully boot. After the progress bar completes the screen goes to grey and then black and starts over again and again. I've tried setting the PRAM and completely pulling the power. The first clue was a couple of days ago when during normal use (on YouTube) the screen just suddenly went black and everything shut down automatically. Then after rebooting the machine would only last about 10-15 minutes before going black again. And now, it won't even get through the restart cycle without this endless loop of auto-rebooting.

iMac 27", macOS 10.13

Posted on Feb 26, 2019 9:10 AM

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Answer 1

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leroydouglas

Community+ 2024

Level 10

183,918 points

Feb 26, 2019 10:32 AM in response to Phil Naccarato

See if you can Boot into Recovery (Command R) and from the dropdown menu: Utilities> Disk Utility> run the First Aid on your Macintosh HD. If errors are found and repaired, run again until no errors reported. 

Recovery http://support.apple.com/kb/HT4718

Try a SafeBoot https://support.apple.com/en-us/HT201262

Takes noticeable longer to get to the login screen, does a 5 minute disk repair before it fully boots up, and certain system caches, dynamic loader cache, etc. get cleared and rebuilt.

If no resolve and If no errors—from this same recovery —you can quit the DiskUtility and from

Utilities menu drop down>Reinstall the macOS on top of your existing macOS, leaving your user data/files untouched

Always have current backup plan.

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Imac won't fully boot

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