Can't recover, can't reinstall; now what?

[modernhistorian]

Using an imac II with i5 2.66GHz and 500 GB SSD. An update around June 23 broke the restart/shutdown process and the mac could only be shut down by holding the power button. Using shift-option-command-R, I tried to recover from time machine, but the mac won't boot after that. I tried to reinstall from the net, but I get some kind of "Preboot volume" error, apparently because the new file system broke the SSD. I tried deleting the volume, but it will only allow me to add it back as an AFSD (or whatever it's called) volume.



I'd like to go back to Sierra, but I can't recover a pre-High Sierra setup from time machine. I read about booting from a usb copy of Sierra, but how can I get that if my mac doesn't work? The original disks, which I think may have been Leopard, are long gone. Please, can someone explain how to reinstall Sierra on this machine? Thanks.

 

[Fishrrman]

What is an "iMac II" ?
What year was it made?
What is the display size?

Did you install the SSD yourself?
Could it have failed?

 

[modernhistorian]

2011, I think, or maybe later. I don't think I can get to "about this mac" for further info. Display is 27 inches. I installed the SSD and used it for more than a year with no problems. Disk utility is not reporting any problems with the drive now. Thanks for help.

 

[BLUEDOG314]

Your machine is likely fine, APFS is just a little different to deal with.

Here's whats good. I assume you are backed up because this will erase the drive. Do CMD+Option+R at boot to go to internet recovery, leave out the Shift key. When you get to recovery, open terminal and do 'diskutil erasedisk apfs "Macintosh HD" disk0' without the ' ' around the command. If this command works, then exit terminal and choose the reinstall MacOS option and you should be good. If the command doesn't work take a picture of the screen and post here and I'll help you the rest of the way.

 

[modernhistorian]

I found the tiny serial number printed on the underside of the base and my mac was made before 2011. So, no internet recovery for me. I can't use the terminal diskutil commands because disk0 can't be unmounted. Is there a way to copy, using terminal, /dev/disk2, which contains the OS X Base System, onto a USB drive and make it bootable? Then perhaps I could boot that, use disk utilities to erase Macintosh HD and format it as Mac OS Extended, and use Time Machine to recover a Sierra backup. Thanks for your help.

 

[BLUEDOG314]

At this point I would say download the installer on another mac and make that bootable, then use it to erase and reinstall the OS.

 

[modernhistorian]

At this point I would say download the installer on another mac and make that bootable, then use it to erase and reinstall the OS.

Got it working again; this is how: put 4 GB flash drive in, used disk utilities to erase and restore with OS X Base Image, booted to that, erased Macintosh HD and formatted with GUID Partition, and restored from my last Sierra system backup on time machine.

I won't go past Sierra again on this machine. I think that maybe the new file system and older macs don't play well together. Thanks to all for pointing me in the right direction.

 

[chrono1081]

This may or may not be of use but when I would run into trouble reinstalling on older Macs it was because the system time. There is a command (sorry all I can find is youtube video links and its blocked at work) that you run from the command prompt in the recovery utility and you set the time with that. Afterwards the install usually works flawlessly.