How to start iMac that is non-stop rebooting itself?

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Level 1

8 points

How to start iMac that is non-stop rebooting itself?

Help!

When I try to start my computer, watching the progress bar fill up under the Apple icon, the screen will suddenly go black. Then the loud sound indicating it is rebooting and then the screen appears once again asking for my password. It repeats this over and over. (It is possible that this happened while trying to update to the new OS.)

I just tried both the chat and telephone support options but neither one of them works. Thanks for any suggestions you can offer!

iMac 27″, macOS 11.3

Posted on Jun 4, 2021 2:23 PM

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Answer 1

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Limnos

Level 10

411,253 points

Jun 4, 2021 2:31 PM in response to Omip

If your Mac spontaneously restarts or displays a message that it restarted or shut down because of a problem, click here --> https://support.apple.com/HT200553

See if it starts in Safe Mode.

Use safe mode to isolate issues with your Mac (formerly: Try safe mode if your Mac doesn't finish starting up (formerly: What is Safe Boot, Safe Mode? (Mac OS X))) - http://support.apple.com/HT201262 - "You can use safe mode to help you resolve issues that might keep your Mac from completely starting up."

If it starts then there's several things you can try but a good place to start is to see what's in your startup items for your user in System Preferences > users

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Answer 2

Old Toad

Level 10

207,679 points

Jun 4, 2021 2:48 PM in response to Omip

If you have problems booting into Safe Mode or the Recovery volume it could be the wireless keyboard. If you have a wireless keyboard with rechargeable batteries connect it with its charging cable and try again. The cable turns it into a wired keyboard.

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Answer 3

Omip Author

Level 1

8 points

Jun 11, 2021 1:18 PM in response to Old Toad

Thank you, Limno and Old Toad. I appreciate your answering my question. It turns out that the computer had gotten stuck trying to update the new Big Sur OS. I was able to get Apple Support to walk me through the process (which took nearly 24 hours!) and am happy to have succeeded. However I lost a lot of my apps and settings. Thanks again.

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How to start iMac that is non-stop rebooting itself?

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