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?

  • You mentioned RAM in the second paragraph. Did you initially add other RAM before this happened? When it doesn't boot, do you get any errors on the screen, a series of tones from the speaker, or just a blank screen?
    – IconDaemon
    Commented Apr 21, 2021 at 15:01
  • Hello, does any error message appear when you try to start your device? You said you changed the RAM. Was this error there before you exchanged anything? You also said that you completely erased your hard drive. Since you said yes, that you cannot boot, I suppose you took out the hard drive and deleted it somewhere else. How did the problem arise?
    – BabyBoy
    Commented Apr 21, 2021 at 16:58
  • I don't really get an error message but every time I start up I get the Apple logo with the progress bar but it won't fully go through.
    – Morreeuh
    Commented Apr 22, 2021 at 8:12

1 Answer 1


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:

  1. Start Apple Configurator 2 on the second Mac and connect the Mac computers.
  2. Restart the Mac using a specific key combination.
  3. 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

  1. 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.
  1. Connect the USB-C cable (along with any necessary adapters).

Step two: prepare your Mac

  1. Connect a monitor so you can see when the process is complete.
  2. Unplug your Mac from its electrical outlet for at least 10 seconds.
  3. Press and hold the power button.
  4. Reconnect to the power supply while continuing to hold the on / off button.
  5. 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

  1. Press the power button.
  2. 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

  1. 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"

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .