IMac – My iMac won’t boot ( internal and external )

boothard driveimac

My iMac won't boot from an internal drive, even when I completely wipe it and reformat it and start up with command shift R.

Then I tried booting it from an external drive, but even then it wouldn't boot at all. I even tried other RAM so it shouldn't be the problem in this case.

It's a 27" iMac 2012.

Are there other things I can try?

Best Answer

Repair or restore a Mac in Apple Configurator 2

If there is no way to get the Mac working again, you will need a second Mac.

The firmware must be restored and the internal flash memory must be deleted if the following situation occurs:

The Mac cannot start from Startup Disk or RecoveryOS.
The firmware repair failed.

Repair or recovery process

The repair or recovery process consists of the following steps:

Start Apple Configurator 2 on the second Mac and connect the Mac computers.
Restart the Mac using a specific key combination.
Use Apple Configurator 2 to do one of the following: Repair firmware and reinstall the latest version of RecoveryOS Restore firmware, erase all data, and reinstall the latest version of RecoveryOS and macOS

Step 1: Configure Mac with Apple Configurator 2 and connect the USB-C cable

Make sure of the following:

You have installed the latest version of Apple Configurator 2.
Your Mac is connected to the electrical outlet.
You can connect to the internet.

Connect the USB-C cable (along with any necessary adapters).

Step two: prepare your Mac

Connect a monitor so you can see when the process is complete.
Unplug your Mac from its electrical outlet for at least 10 seconds.
Press and hold the power button.
Reconnect to the power supply while continuing to hold the on / off button.
Release the power button.

Note: You will not see any Mac activity on the screen during this time

Step 2: prepare your Apple notebook computer

Press the power button.
Hold down your power button while simultaneously pressing the following three buttons for about 10 seconds:

the right shift key the left option key the left Control key

Immediately release the three buttons after 10 seconds, but keep holding the power button until it appears in Apple Configurator 2.

Note: There is no activity on the Apple notebook computer on the screen during this time.

Step 3: Repair the firmware and install the latest version of the RecoveryOS

In the Apple Configurator 2 device window, select the Mac whose chip firmware is to be repaired and whose RecoveryOS is to be updated to the latest version, then select

Actions > Advanced > Repair device and click on Repair.

Note: Hold down the "Control" key and click on the selected device, choose "Advanced" > "Repair Device" and click "Repair"

Related Solutions

MacBook won’t boot from internal SSD

I don't know how it worked without issues for over a year... but the culprit is probably the drive cable. To put a long story short, the interface is SATA III on the motherboard, it's SATA III on the SSD, so they will talk SATA III.

But if your MBP shipped with a SATA II HDD, it most likely came with an interconnect cable only rated for SATA II.

I wouldn't have thought this would be that big of an issue (I sort of thought the difference was like the difference between a CAT 5 and CAT 5e UTP) but apparently with the models of SSD's on the market right now and their throughput, it causes an issue.

I couldn't tell you how to determine if the cable's the "updated" SATA III version or not when shopping for parts, but I do know that this one is.

IMac won’t boot to internal drive, usb sticks – Apple hardware test extended fine

You should try to boot your OS in verbose mode or safe mode to see whether you can fix it or not.

https://support.apple.com/en-us/HT201262

https://support.apple.com/en-us/HT201573

If you really need to reinstall Mac OS X Yosemite, I'd suggest you run this script from any Mac, you need to have Yosemite downloaded in /Applications.

#!/bin/sh
# Mount the installer image
hdiutil attach /Applications/Install\ OS\ X\ Yosemite.app/Contents/SharedSupport/InstallESD.dmg -noverify -nobrowse -mountpoint /Volumes/install_app

# Convert the boot image to a 8GB sparse bundle
hdiutil convert /Volumes/install_app/BaseSystem.dmg -format UDSP -o /tmp/Yosemite
hdiutil resize -size 8g /tmp/Yosemite.sparseimage

# Mount the sparse bundle for package addition
hdiutil attach /tmp/Yosemite.sparseimage -noverify -nobrowse -mountpoint /Volumes/install_build

# Copy Packages and Base System files to the sparse bundle
rm /Volumes/install_build/System/Installation/Packages
cp -rp /Volumes/install_app/Packages /Volumes/install_build/System/Installation/
cp -p /Volumes/install_app/BaseSystem* /Volumes/install_build/

# Unmount the installer image and sparse bundle
hdiutil detach /Volumes/install_app
hdiutil detach /Volumes/install_build

# Resize the partition in the sparse bundle to remove any free space
hdiutil resize -size `hdiutil resize -limits /tmp/Yosemite.sparseimage | tail -n 1 | awk '{ print $1 }'`b /tmp/Yosemite.sparseimage

# Convert the sparse bundle to ISO/CD master
hdiutil convert /tmp/Yosemite.sparseimage -format UDTO -o /tmp/Yosemite
rm /tmp/Yosemite.sparseimage
mv /tmp/Yosemite.cdr ~/Desktop/Yosemite.iso

Credit goes to the person who wrote that script for Maverick

You can then restore the ISO using Disk Utility on a 8Gb USB Stick and it will be bootable.

Best Answer

Repair or restore a Mac in Apple Configurator 2

Related Solutions

MacBook won’t boot from internal SSD

IMac won’t boot to internal drive, usb sticks – Apple hardware test extended fine

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