My iMac Died
I bought a used 2020 iMac about a month ago and things started going wrong about a week ago. Yesterday my iMac gave up the ghost and nothing I did brought it back to life. It’s a brick.
Here’s the story . . .
First, during the past week the “Mac screen of death” appeared more and more. My iMac would freeze and then restart with this screen:
After too many of these screens of death, I decided to reinstall the MacOS on my iMac. However, first I tried running the Mac’s Disk Utility First Aid, but that failed. After several attempts, First Aid kept failing.
Next, I tried cold starting the iMac while holding down the CMD and R keys in order to enter Recovery Mode.
INTERNET RECOVERY
However, after several minutes, this screen appeared:
Before my next attempt, using my MacBook laptop, I created a bootable external USB drive with MacOS installed.
EXTERNAL BOOTABLE MAC OS DRIVE
Then I connected the drive to my iMac, and restarted my iMac while holding down the Option key:
When the possible startup disks appeared, I selected the external USB drive I had just created (IMACSTARTUP):
However, 2020 iMacs have the T2 security chip installed which prevent start up from an external disk:
So . . . . another CMD + R restart . . .
I “passed” the first part of the T2 security chip procedure . . .

Finally, I thought I was getting somewhere. I selected “Exit to Recovery” and then selected the “Startup Security Utility” in order to get around the T2 security chip:
But once again I was thwarted because the Startup Security Utility would not accept my login password:
Nevertheless, from my college UNIX days I opened the Terminal program and entered the resetpassword command:
Failure again! (I love the two “choices” on the screen below.)

TIME MACHINE BACKUP ATTEMPT
Next, still in Recovery mode, I tried a Time Machine backup:
This too failed as it wanted me to install MacOS first.
MAC OS REINSTALL ATTEMPT
So I tried re-installing the MacOS on my iMac (Macintosh HD):

The MacOS reinstall started ok . . .
However, once again, it failed because of a hard disk error:
DISK UTILITY FIRST AID
Last chance — in Recovery I ran Disk First Aid on my iMac disk:
That’s it. Nada.














