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Latest update just killed my iMac

N

neale68

macrumors newbie
Original poster
Feb 28, 2018
3
0
Yesterday I booted my iMac for the first time in about four weeks (A1224) and it told me an update was needed and to restart it to finish. I restated and it hasn't booted since. The update was something to do with High Sierra, but I didn't really tale much notice.

It starts the boot up procedure. It bongs, I get the apple in the middle of the screen and the progress bar gets to about half way, then the screen goes off, and occasionally flashes on. When it flashes, i can briefly see the progress bar and it doesn't move. It was left on all day yesterday like this, flashing every 5 to 10 seconds, with no progress.

I have tried booting up safe mode and it does exactly the same thing except the flashing screen is opposite. ie it flashes off briefly every 5 to 10 seconds but is mainly on.

I have tried the reset NVRAM startup and also the reset SMC startup. neither made any difference at all.

Is there anything I can do to get the machine back to how it was before it tried to install this update?

Last time I used it I did take a Time Machine backup, so I have this.

I do not have any original OS stuff as I bought it 'refurbished' with the OS already installed.

Can anyone help, i'm getting desperate.

Thanks
 
neale68 said:
Yesterday I booted my iMac for the first time in about four weeks (A1224) and it told me an update was needed and to restart it to finish. I restated and it hasn't booted since. The update was something to do with High Sierra, but I didn't really tale much notice.

It starts the boot up procedure. It bongs, I get the apple in the middle of the screen and the progress bar gets to about half way, then the screen goes off, and occasionally flashes on. When it flashes, i can briefly see the progress bar and it doesn't move. It was left on all day yesterday like this, flashing every 5 to 10 seconds, with no progress.

I have tried booting up safe mode and it does exactly the same thing except the flashing screen is opposite. ie it flashes off briefly every 5 to 10 seconds but is mainly on.

I have tried the reset NVRAM startup and also the reset SMC startup. neither made any difference at all.

Is there anything I can do to get the machine back to how it was before it tried to install this update?

Last time I used it I did take a Time Machine backup, so I have this.

I do not have any original OS stuff as I bought it 'refurbished' with the OS already installed.

Can anyone help, i'm getting desperate.

Thanks
Click to expand...

Are you able to get into the Recovery Mode? If so, and you have that Time Machine backup, follow Apple's instructions here: About macOS Recovery

This all said, the visualization you paint would have me wondering if it's hardware related that just hit at the same time as the reboot.

There's two things at play, remember - the update AND the reboot - doesn't necessarily mean the update did the damage, it could have been the reboot...
 
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Thanks for a quick reply. I'll have a go at the recovery mode option. Didn't realize that was a thing! Fingers crossed I get somewhere.
 
Thank you TiggrToo. I am up and running again after a restore from Time Machine. So happy I did teh back up. Its the only time I have ever done it! It has reverted to El Capitan, which I guess I must have been on before the upgrade. The big question now is: Do I attempt to upgrade to HS or leave it on El Capitan?
 
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I'd leave it on El Capitan and be happy.

(Provided that there is no really specific reason why you NEED High Sierra...)
 
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