Late 2012 27" iMac Won't Boot

Question

Late 2012 27" iMac Won't Boot

I've been considering recycling this thing for a month or so but figured I'd try one more time to get it back up and running before I tossed it. Any suggestions are appreciated. Thanks.

I have a late 2012 27" iMac with a fusion drive that I'd kept around for some old device compatibility. I used it infrequently, maybe once a month. A month or 2 ago I had to hard shut down because it had

apparently frozen in it's sleep. Now all I can get is a white screen with the Apple logo and 1 pixel of progress that never goes any further.

If I listen closely to it I can hear the HDD spin up when I power it on. Over the gong and fans it is hard to hear if it's making any unusual noise, but I don't think it is. It does not sound like it is actively

doing anything once it's spun up.

I want to say the OS is 10.12 or 10.13. Maaaaaaybe 10.4 tops.

I attempted the following, all of which results in a blank white screen:

Command + R - Mac OS Recovery
- Command + Option + R
- Command + Shift + Option R
Option - Startup Manager
Shift - Safe Mode
D - Apple Diagnostics
T - Target Disk Mode (although I don't have the right cable to connect this to any other computer at the moment)

I plugged in an external monitor via Thunderbolt to HDMI but it never gets far enough along to recognize it and display anything on it.

I have had minor success with:

Resetting the PRAM. I can hold Command + Option + P + R and get the startup gong to fire and reboot and repeat if I keep holding it. It hasn't helped with the problem so far though.

The only thing plugged in is a wired Apple keyboard (USB A1243). The escape key does not work but all others do, verified on my Mac Mini. I do have some other PC keyboards available.

Other Macs I have available if they can come in handy:

2018 Mac Mini
2016 MacBook Pro 15"

Posted on May 30, 2021 10:28 AM

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Answer 1

Best reply

Rafael Scheid

Level 5

5,334 points

May 30, 2021 11:32 AM in response to Sean C. Carter

I didn't see you talk about resetting SMC. Try this How to reset the SMC of your Mac - Apple Support and this If your Mac starts up to a blank screen - Apple Support

Do you have an external drive? Install macOS on it using your Mac mini How to create a bootable installer for macOS - Apple Support, plug it in the iMac and start holding Option, choose the external drive to boot and check if it goes up all the way.

Additional info If your Mac doesn't turn on - Apple Support, If your Mac doesn't start up all the way - Apple Support

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Answer 2

Old Toad

Level 10

208,127 points

May 31, 2021 12:34 PM in response to Sean C. Carter

To see if the drive is what failed try booting it into Target Disk Mode . If it boots then the drive is OK and the problem lies elsewhere.

I removed the drives from a 2011 iMac that had a 256 SSD and 1TB HD (not a fusion drive). The HD was easy to get to but the SSD was way back under the mother board. It was a good thing that I was recycling the machine as I never would have been able to put it back together in any reasonable form afterward.

If the drive is good you can copy the data off it it in Target Disk Mode and then erase it before recycling.

If the drive is not good you'll have to make the decision to recycle the drives along with the iMac or remove the drives beforehand.

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Answer 3

May 31, 2021 10:06 AM in response to Rafael Scheid

Thanks for the reply, Rafael.

Correct that I did not attempt resetting the SMC. I just gave it a go, no luck in seeing any improvement.

Had some trouble getting the App Store to cooperate with downloading an OS to make an installer, but finally just got that done and unfortunately the iMac still does not like when I hold Option at startup. I just get stuck at a white screen.

I appreciate your suggestions!

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Answer 4

Jun 1, 2021 7:20 AM in response to Old Toad

Thanks for the reply Toad.

Target Disk mode also leaves me stuck at a white screen. I think it's time to call the time of death on this guy! It served me well, but I sure wish Apple made it possible to use as an external display once the computer is past it's useful lifespan. It's really nice looking machine and display.

Thanks for the help. Time to start gutting it so I can pull the drives out and wipe or destroy them. Should be a fun project. I haven't opened up an iMac since the CRT days!

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Answer 5

Jun 1, 2021 8:16 AM in response to Sean C. Carter

Not yet, bro. Hold on.

Get an external drive and hook it up to a working Mac, install macOS on this drive, set it up completely so you won’t have to face the process in your Mac and then hook the disk to your Mac and start from it.

If this works, your Mac is probably Ok and internal disks are not.

I insist on it because your Mac boots and you’re able to get to boot menu to start from a usb drive, for exemple, which means basic hardware is passing through POST.

I really want to see it alive 💪🏼

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Answer 6

Old Toad

Level 10

208,127 points

Jun 1, 2021 9:55 AM in response to Sean C. Carter

My 2011 iMac was the last year they held the screen on with magnets making it reasonable easy to remove the screen. The next year they began gluing the screen on so you're going to have a more difficult time getting it off.

I had fun doing it as I didn't have to worry about putting it back together correctly. Like a kid in a candy store.

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Answer 7

Jun 1, 2021 1:41 PM in response to Sean C. Carter

Oh man…

Let’s try again in a sequence

Reset SMC

Reset NVRAM

Restart holding Command V. Let’s see if it starts verbose mode and if we can read some of the boot log and where it hangs at (this might replace the white screen for a text boot screen).

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Answer 8

Jun 1, 2021 4:09 PM in response to Rafael Scheid

OK this got me some new behavior.

1st try:

Reset SMC (OK), Reset NVRAM (OK), Restarted holding Command V and this time I got a white screen and it was stuck in a loop playing a tiny fraction of the startup gong.

2nd try:

This time when I got to the NVRAM part it stuck on a black screen and never played the gong again.

3rd try:

Reset SMC (OK), Reset NVRAM (this time I held the keys through one more gong just for kicks), Command V - BOOM! Got the black screen with loads of text. Saw some scary sounding stuff as it went by (like unsupported CPU, something of that nature). It went away before I could snap some pictures, and then it tried to boot up. Got a white screen with Apple logo and progress bar that went slightly further than I had seen before (previously about 1 pixel width, this time about 3 pixels) and stuck again.

Now I can't get it back. I've tried more than half a dozen times more with a camera recording the screen, so I can capture the text it was displaying, and it won't do it again. Just white screens over and over. This is wild. I'm going to unplug it and let it take a breather and try again tomorrow. Feeling bummed after that spark of possible progress.

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Answer 9

Jun 6, 2021 12:15 PM in response to Sean C. Carter

Alright I think I'm throwing in the towel. Tried again this morning and could not get the Verbose boot screen to come up, all other commands still only result in a white screen. Doesn't show an Apple logo anymore at any point. Time to pull the drives!

Thanks for all your help and suggestions!

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Answer 10

Jun 1, 2021 9:03 AM in response to Rafael Scheid

Hi Rafael,

Actually I have not been able to get to the boot menu. Holding option results in a blank white screen. I'm game if you think it's still worth a shot though!

-Sean

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Late 2012 27" iMac Won't Boot

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