Cannot boot iMac - Suspected Hardware Issue
Hi Guys,
In summary, my iMac (late 2012) is not starting up and I would really appreciate some expert help! :)
Problem
On start-up, the following steps occur in a loop:
- I hear the chime.
- Apple logo appears.
- Loading bar gets to approximately seventy-five per cent.
- Error message displayed: 'Your computer restarted because of a problem. Press a key or wait a few seconds to continue starting up.'
- Automatic reboot.
Suspicions
I suspect there are two problems:
- The hard drive boot and/or recovery partitions are corrupt because I can access the main data partition using Target mode and Single User mode. But the bigger problem I think is…
- There is also some other hardware problem that stops me using the other recovery modes or booting from a bootable USB stick. If this is the case, then I guess I just need to give up!
Hopes
My only hope is that there might be some additional steps I can perform in Single User mode to recover from this situation and this is where you come in. :)
All data is backed up so this is merely an attempt to see if I can recover the hardware and hopefully not have to throw this iMac away.
Still in Progress
I am still in the process of trying to run fsck via Single User mode, but I can’t see how this will help due to the suspected hardware issue above (#2) which stops me reinstalling the operating system, even if I can repair the hard drive.
Hardware
- First thing I tried was unplugging all hardware apart from a keyboard to access start up key recovery options.
- I also plugged in a mouse when required.
- I tried plugging these into different USB sockets in case there was a problem with one of the sockets.
- I also removed all memory and tried different combinations of memory sticks in different slots in case the memory or the slots were broken.
- None of the above made any difference to the results.
Summary of Recovery Start-up Key Results
- These modes succeed:
- Reset NVRAM/PRAM
- Single User mode
- Verbose mode
- Target mode.
- These modes fail:
- Boot to external drive
- Recovery (local or network)
- Safe mode
- Diagnostics (local or network)
Here are the detailed results of attempting each of the available boot up options...
Reset NVRAM/PRAM (Option-Command-P-R)
- Succeeds.
Single User Mode (Command-S)
- I’m still investigating the available options including fsck.
- Any advice would be appreciated.
Verbose Mode (Command-V)
- Lots of output displayed in console, then the ‘Your computer restarted because of a problem.’ error is displayed and machine reboots.
- I have a video of the console output which I have still to analyse to see if there are any clues there.
- If anyone has any suggestions of what to look for that would be appreciated.
- I suspect there is a key piece of information there but most of the output is meaningless to me.
- I will report back once I have investigated but the last couple of entries logged are:
- TODO
Target Mode (T)
- Succeeds.
Boot to external drive / Start-up Manager (Option)
- The boot manager screen appears.
- After selecting a bootable drive (tested on another mac), the following occurs:
- Apple logo appears.
- Loading bar gets to approximately fifty per cent.
- System hangs.
- Have tried more than bootable disk but the result is always the same.
Recovery (Command-R)
- Apple logo appears.
- Loading bar gets to approximately fifty per cent.
- System hangs.
Networked Recovery (Option-Command-R)
- Enter Wi-Fi password.
- This is because I unplugged all unnecessary hardware.
- If I startup with ethernet cable, the results are the same apart from having to enter Wi-Fi password.
- For a while I see a spinning globe and this message: ‘Starting internet recovery this may take a while.’
- Apple logo appears.
- Loading bar gets to approximately fifty per cent.
- System hangs.
Safe Mode (Shift)
- Apple logo appears.
- Loading bar gets to approximately eighty per cent.
- System hangs.
Networked Diagnostics (Option-D)
- Enter Wi-Fi password.
- This is because I unplugged all unnecessary hardware.
- If I startup with ethernet cable, the results are the same apart from having to enter Wi-Fi password.
- For a while I see a spinning globe and this message: ‘Starting internet recovery this may take a while.’
- This was unexpected for the local diagnostic tool. I suspect because the recovery partition is not available.
- Screen goes black and displays errors:
- Error 0x8000000000000003, Cannot load EFI/Drivers/TestSupport.efi
- Status 0x00000003
- After a couple of minutes the system reboots and the ‘Your computer restarted because of a problem’ error is displayed.
Diagnostics (D)
- Exactly the same as the networked version which was unexpected for the local diagnostic tool.
iMac 27″, macOS 10.15
