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User profile for user: PolarBear1342
PolarBear1342 Author
User level: Level 1
27 points

iMac 2009 corrupt HD after update!!!

Hello guys. I just tried to update my old 2009 iMac (was running 10.6.8) to High Sierra, but the update failed in many ways. So I made myself a bootable USB where I can install High Sierra from. So I partitioned the Macintosh HD and installed High Sierra on the free partition. Then, suddenly, with about two minutes remaining in the installer on the bootable USB, the mac shut down unexpectedly. It restarted and said "Your Mac shut down because of a problem" or something the sort. Now, when I start it up, it shows a High Sierra style apple logo and loading bar, but then the screen goes black, the Macintosh HD makes weird noises, and the same process happens over and over again until it tells me my mac shut down because of a problem. I booted in verbose mode, and it tells me that the mac is booting after panic. I cannot access recovery and when I press OPTION to select bootable disk and boot from the USB the Mac logo is replaced with a circle and a line through it.

Help would be very appreciated!

I'm fine with erasing my disk and getting back to 10.6.8 or High Sierra. The computer just has to work again.

Thank you so much!

iMac Line (2012 and Later)

Posted on Oct 21, 2019 8:00 AM

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User profile for user: ProbsRus
ProbsRus
User level: Level 4
1,126 points

Posted on Oct 21, 2019 8:55 AM

If you have access to another Mac have you considered placing your iMac into Target Disk Mode by turning on the iMac and immediately pressing and holding the T key while it starts up? Once in Target Disk Mode your iMac will act like an external hard drive that you could connect to a known good Mac with the appropriate cables so that you can format the hard drive, run Disk First Aid to confirm it is in good shape, etc. Hopefully reformatting the affected partition, or the entire hard drive, will get you out of the boot loop and allow you to reinstall macOS onto it.


Use target disk mode to move files to another computer - Apple Support

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User profile for user: ProbsRus
ProbsRus
User level: Level 4
1,126 points

Oct 21, 2019 8:55 AM in response to PolarBear1342

If you have access to another Mac have you considered placing your iMac into Target Disk Mode by turning on the iMac and immediately pressing and holding the T key while it starts up? Once in Target Disk Mode your iMac will act like an external hard drive that you could connect to a known good Mac with the appropriate cables so that you can format the hard drive, run Disk First Aid to confirm it is in good shape, etc. Hopefully reformatting the affected partition, or the entire hard drive, will get you out of the boot loop and allow you to reinstall macOS onto it.


Use target disk mode to move files to another computer - Apple Support

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User profile for user: PolarBear1342
PolarBear1342 Author
User level: Level 1
27 points

Oct 21, 2019 2:50 PM in response to PolarBear1342

I don't have a USB to USB or a FireWire to USB cable, so I looked at my options. In my MacBook Air box, which is by the way full of Apple stickers, is a little white thing I should insert into one of the sides of the USB ports. I did this on my iMac and I somehow managed to boot off it and erase the HD. It turns out I had two partitions. I don't know how I got into this mess. But now I'm reinstalling OS X 10.6.8 from my backup. I'll keep you guys posted, but thanks for your reply. This would probably have been a lot easier had I a USB to USB cable!

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iMac 2009 corrupt HD after update!!!

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