What I learned from deleting my restoreOS partition…

TL;DR DON’T DO IT

Now for the longer version of the story. Last week I was fumbling around formatting a handful of USB thumb drives on my M1 Macbook Air, and I sadly formatted the restoreOS partition. While I was in a quick panic mode when I noticed and tried to stop the process, the damage has already been done. With that being said I didn’t think much of it as previously I could simply create a macOS installer from a USB thumb drive, boot from that, and reinstall without issue as I had done with every previous Macbook I have owned… sadly I learned this was not possible due security aspects surrounding newer machines.

I looked up the details online and it seemed simple enough to fix, using just a USB cable to connect it to another Apple computer, and using the Apple Configurator 2 app. I didn’t think that I had a cable so I booked a same-day appointment with the local Apple Store hoping this would be a walk-in, explain the issue, have them run the fix and then be on my way home.

Sadly upon arrival at the Apple store I explained the issue, the tech confirmed it and I was then told it would be 24hrs before I could pick it up. This was just not going to work as I still had work the rest of the day and week for that matter. I decided to take my chances and head home to look for a USB cable in one of the many boxes in my office.

Thankfully I was able to locate one, still in the packaging from when I saw a good deal on Amazon and thought I should buy it just in case lol. After work, I set out to see if I could perform this fix. It took me a couple of tries to get it into DFU mode, but once I did the rest was fairly easy as explained below.

Steps for putting you placing the M1 Macbook Air into DFU mode.

  1. Plug M1 Macbook Air to host Mac using a DFU cable, in my case it was a USB-A -> USB-C Cable. Make sure that you use the port on the furthest corner of laptop.
  2. Shut down the M1 Macbook Air
  3. Press together: Right SHIFT, Left CONTROL, Left OPTION
  4. While you hold all 3 keys, press and hold the power button.
  5. Count to 10, then release all keys except the power button. (You should see the Apple logo while you count, just ignore it.)
  6. Continue to keep the power button pressed for 10 additional seconds, then release the power button
  7. The display should be black, this is normal.

If you take a look at the other Mac running the Apple Configurator 2 app, you should notice your M1 Macbook Air shows up with a DFU icon. If it does not have the DFU icon you will need to repeat the steps as it was not successful. After getting to the proper DFU mode you can now restore the Macbook. You may want to try the “Revive” feature under Advanced, it sadly was not able to Revive mine and I had to go the extreme route of restoring it to factory condition.

All said and done once I got it into DFU mode it took about 30 minutes to complete, and then since I had a recent backup I was able to restore all the files on my laptop over the course of about another hour… far from the 24hrs I would have had to have left it at the Apple store.