I tried to install some updates on my Macbook Air. I received a notification asking if I wanted to restart the Macbook to install the updates, I accepted and restarted. When booting, the Apple logo appears, the progress bar starts loading but then stops at some point showing the message:
A software update is required to use this startup disk. You can update now or select another startup disk.
I select the Update button, at which point the progress bar starts loading again, but it interrupts almost immediately showing the message:
An error occurred installing the update. Try again or select another startup disk.
I select the Try Again button, but the same message shows again. I then select Startup disk, and I am asked to Select the system you want to use to start up your computer. The list, however, is empty! At this point I don't know what to do, there are basically no options or buttons that I can press.
If I select the Startup disk button first, instead of the Update button, I get the same empty list of Startup disks to choose from.
Any idea what can have gone wrong and how to fix it?