Factory Reset

The display was removed, things were looking clean.

This is a used device. It seemed like the OS was a fresh install, but I like to be sure, so I did a factory reset. The process seemed smooth, until the reboot.

I wasn’t sure how long to wait for boot after a factory reset. I’ve had some devices (eg Android phones after installing custom ROMS) take many minutes on first boot after a reset, but online info suggested this should be pretty quick on an M1 Mac.

Minutes passed and the display wasn’t showing anything. I wasn’t sure what was going on, and I started playing guessing games with the power button. I wished again that there was a power LED. With the broken screen removed I couldn’t even rely on those few lines of pixels lighting up to give me clues.

I’m still not sure if I broke/interrupted something, or if this was a normal part of the reset process. I tried various patterns of tapping, holding, holding for longer, each time waiting for something to happen for 10, 30 or 60 seconds. How long should I wait before I expect to see something on the screen?

Eventually I got something to happen. I was back to the black (but lit/powered on) screen. I guessed I was somewhere mid-boot. I tried the CMD + F1 combo which had made the external monitor primary when I was on the login screen. It didn’t work – the key combo/switching must be a feature of MacOS, which I was not yet booted into. A little reading around online hinted that I might be in recovery mode.

I found a video explaining how recovery mode worked on a machine with an external monitor and no internal display, and how to handle it.

Recovery mode when you only have an external monitor

The situation is this:

• Recovery mode recognises your external monitor, but treats it as an extension to the internal display
• The window with all of the useful user interface is there, but it’s ‘on the internal display’ (whether that exists or not)
• The phantom internal display is drawn off to the right of the external monitor

In my case, the resolution of my external monitor was smaller in height than the internal monitor. This may have made the situation more confusing. I think that the top menu bar extends across both displays, and if my monitor was tall enough I’d have seen the bar, giving a massively more helpful clue than the empty black screen.

• MacOS Recovery Phantom Screen

To get stuff done in recovery mode, you have to drag the window from phantom screen, onto the external display. The window is only draggable by its title bar. So you have to shoot your touchpad pointer off the right-hand side of your screen, aim for where you think the title bar might be, and try to tap/drag it back over to your real visible screen on the left .

This took me ages. I think the window on the invisible screen was centred, but because it was a different resolution to my monitor it was hard to visualise and aim for it. But once done, I could access everything in recovery mode.

After finishing the reset I booted. The monitor doesn’t start showing stuff until later in the boot process but that’s ok.

I’m in, on the external monitor, with the Macbook’s internal screen removed.