iMac freezes at startup

Question

Level 1

22 points

iMac freezes at startup

I'm helping a friend with a 27" iMac (no optical drive so 2013?) which refuses to start. The progress bar gets about a quarter of the way across then freezes.

I've managed to start in safe mode once but it won't do it again. I've reset the PRAM and SMC to no avail. I have been able to start from the recovery partition and repair the drive - no errors found - and repaired permissions although I didn't expect that to achieve anything!

I'm now leaning towards it being a hardware fault, perhaps RAM, perhaps something else. Before we undertake a hernia inducing trip to the Apple store, anything else I can try?

Posted on Mar 29, 2016 9:32 AM

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Answer 1

theratter

Level 4

3,955 points

Mar 29, 2016 9:40 AM in response to macfan7

Try each of these in order. Test to see if the computer is working properly:

Repair the disk by booting the from the Recovery HD. Immediately after the chime hold down the Command and R keys until the Utility Menu appears. Choose Disk Utility and click on the Continue button. Select the indented (usually, Macintosh HD) volumeentry from the the side list. Click on the First Aid button in the toolbar. Wait for the Done button to appear. Quit Disk Utility and returnto the Utility Menu. Restart the computer from the Apple Menu.
Reinstall OS X by booting from the Recovery HD using the Command and R keys. When the Utility Menu appears select Reinstall OS X then click on the Continue button.
Download and Install the OS X El Capitan 10.11.4 Combo Update.

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Answer 2

macfan7 Author

Level 1

22 points

Mar 29, 2016 1:58 PM in response to theratter

Thanks for the reply.

You'll see from my original post I've already repaired the drive - it showed no errors. I've currently avoided reinstalling the OS but as you say that's a possibility. As it won't start, I'd need to use another machine to download the Combo Update - if I start the iMac from this second machine, is it possible to install the update on the iMac drive?

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Answer 3

theratter

Level 4

3,955 points

Mar 29, 2016 2:11 PM in response to macfan7

Not the combo update which must be installed only on the machine being updated. But you could do a full reinstall of OS X from the other machine if you can download the installer on the other machine. If the iMac can be booted from the OS version installed on this other machine, then you could clone the other machine to your iMac. However, you must be able to connect the two either using Firewire and/or Thunderbolt. See about using Target Disk Mode.

You can also do a Network Install, but I don't know if you can do a re-install without erasing or if you can only do an erase and install. You must be connected to the Internet so your computer must either have Wi-Fi or Ethernet connection. You would restart and immediately after the chime press Command-Option-R and hold them down until you see a rotating globe appear.

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