Imac 21,5 inch mid 2011, SSD Crash, can't reinstall OS

Hallo

We got an old Imac 215 inch mid 2011, that got upgraded with an SSD in 2015. The machine is old, but was excellent for my daughter as a browsing, video call and Googledrive device.

Some weeks ago, we exchanged the keyboard and that created a chain of events to made the Imac unusable. First the keyboard lost the Space and backspace function. I tried to fix that (It was not a mechanical issue), reseted the VRAM, but then the machine crashed and eventually we lost the connection to the SSD.

So I reformatted the SSD and wanted to make a clean install of an OS, the last usable seems to be el Capitain. And now that seems to be impossible, this is what I tried so far.

Restart in safe mode, reformat the SSD, Reinstall OS -> always fails at the end of the install
How To Create A Bootable USB macOS Installer, Never managed to get create a boothable USB -> "command not found" in terminal
Got an external SSD, where I put the OS on, doesn't work
Diskmaker X, seems to be too old

Another detail, I still got the original CD's, but the reader is dead

By the way I can still booth the Mac on the old Harddisk, but this is so slow the machine is unusable...

I did verify the SSD with Disk Ultilities, it seems to be OK no Errors, also S.M.A.R.T. seems to be OK

So I am really at a lost now, anyone who got a golden tip on how to revive this machine ? I might buy another SSD, they are really cheap now, but I want to be sure I can get an OS on it.

Thanks,

Samuel

iMac (2017 – 2020)

Posted on May 28, 2023 12:37 AM

Top-ranking reply

WheelieNick

Level 8

46,199 points

Posted on May 28, 2023 2:38 AM

The last macOS supported by your Mac is not El Capitan but High Sierra on a mid 2011 21.5 iMac.

To install High Sierra first download it from this link How to download macOS - Apple Support

After that, grab an usb stick and rename the stick to the name MyVolume. This step is very important otherwise the terminal command will not work.

After that, copy and paste this link (so you cannot make any typo's) in the terminal when the USB drive named my volume is attached to your mac

sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

As all goes right, the terminal is starting to make the usb drive bootable, this can take a while, up to 30 minutes in my experience. When the stick is done, reboot your Mac when holding the option key. You will see a boot selector menu, and you can choose to boot from the stick from there. Select the High Sierra installer and boot in to that one .

If this is not working, you can try it with an external SSD. But make sure that you try to install High Sierra on that one, and not El Capitan. High Sierra also has better compatibility with SSD's in my opinion, as you can use APFS (Apple File System) Maybe your SSD that you're using now is formatted as APFS and that is causing that El Capitan will not install

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