Monterey update bricked 2015 iMac

My 2015 iMac was set for auto-updates

Two days ago it performed a Monterey update. No errors but now it won't boot. Goes to the "prohibited" screen

Disk utility shows the drive is intact, but "writeable" is set to "No"

Option to download Sierra OS hangs at the point where it asks for drive volume. No options are given.

In the "compatible device"s list for Monterey the 2015 iMac is not listed.

If so, why did auto-updates allow this to occur?

Can this be fixed?

iMac 27″, macOS 12.6

Posted on Sep 19, 2022 11:06 AM

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Old Toad

Level 10

214,284 points

Posted on Sep 19, 2022 11:53 AM

See if this Apple document helps: if your Mac starts up to a circle with a line through it

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2 replies

Top-ranking reply

Old Toad

Level 10

214,284 points

Sep 19, 2022 11:53 AM in response to Alec552

See if this Apple document helps: if your Mac starts up to a circle with a line through it

Alec552 Author

Level 1

4 points

Sep 20, 2022 08:19 AM in response to Old Toad

Apple document is no help

Cannot reinstall OS as it apparently does not have write access to the drive. Maybe a permissions problem.

Tried booting from a memory stick. Boots fine but no access to hard drive probably because of security settings.

Seems to be no way to get to the data off the drive. Any suggestions welcome.

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Monterey update bricked 2015 iMac