iMac 2017-stuck on Apple logo, won't recover or allow reinstall

[dawindmg08]

Woke up today to find that my wife's 2017 iMac (5k 27") had restarted during the night and was stuck on the Apple logo screen with no progress bar. Have tried the following with NO success:

1. Multiple restarts
2. Single user mode: 1st try didn't get to prompt (restarted again), next try showed "Attempting system restart...MACH Reboot" into infinity. Now it just panics and reboots.
3. Recovery mode: hangs with progress bar barely started (any recovery mode)
4. Internet Recovery: reboots just after spinning globe finishes
5. Boot from external SSD with Mojave installer: booted once, then kernel panic during attempted reinstall. Progress bar keeps stalling on subsequent attempts
6. Diskwarrior: won't run because latest version of Mojave isn't supported
7. Disk First Aid (via Target Disk Mode): runs, but says disk is "Ok"

Target disk mode is the only thing that works. I'm able to see all the files and back them up, but Mojave installer will not allow me to install in that mode.

At this point I've tried everything I can think of, beyond wiping the drive completely and starting fresh. I have an appt. with a service provider tomorrow and I hope they can find a way to restore the OS without erasing the drive; otherwise, is there anything else I can try on my own? I've never seen a Mac fail to boot into recovery or single user mode and I'm stumped here.

TIA,
D

iMac 2017 5K, 32GB RAM, 1TB SSD, Mojave 10.14.3

 

[chrfr]

Woke up today to find that my wife's 2017 iMac (5k 27") had restarted during the night and was stuck on the Apple logo screen with no progress bar. Have tried the following with NO success:

1. Multiple restarts
2. Single user mode: 1st try didn't get to prompt (restarted again), next try showed "Attempting system restart...MACH Reboot" into infinity. Now it just panics and reboots.
3. Recovery mode: hangs with progress bar barely started (any recovery mode)
4. Internet Recovery: reboots just after spinning globe finishes
5. Boot from external SSD with Mojave installer: booted once, then kernel panic during attempted reinstall. Progress bar keeps stalling on subsequent attempts
6. Diskwarrior: won't run because latest version of Mojave isn't supported
7. Disk First Aid (via Target Disk Mode): runs, but says disk is "Ok"

Target disk mode is the only thing that works. I'm able to see all the files and back them up, but Mojave installer will not allow me to install in that mode.

At this point I've tried everything I can think of, beyond wiping the drive completely and starting fresh. I have an appt. with a service provider tomorrow and I hope they can find a way to restore the OS without erasing the drive; otherwise, is there anything else I can try on my own? I've never seen a Mac fail to boot into recovery or single user mode and I'm stumped here.

TIA,
D

iMac 2017 5K, 32GB RAM, 1TB SSD, Mojave 10.14.3

It sounds like you’ve got some sort of hardware failure. Did you try running the built in Apple diagnostics? Does the computer have 3rd party memory installed?

 

[dawindmg08]

Apple Hardware Test revealed no issues. Same story with First Aid in Disk Utility. It does have RAM from OWC.

FWIW, I've now found a handful of similar threads on here and other sites, documenting the same issue with Mojave. The Mac has some kind of issue and will only boot to the Apple logo but not beyond.

 

[chrfr]

Apple Hardware Test revealed no issues. Same story with First Aid in Disk Utility. It does have RAM from OWC.

FWIW, I've now found a handful of similar threads on here and other sites, documenting the same issue with Mojave. The Mac has some kind of issue and will only boot to the Apple logo but not beyond.

Take the OWC memory out and try again, then if the problem persists, take out the Apple RAM and try with the OWC parts.

 

[Fishrrman]

I agree with chrfr.

The very first thing to do:
REMOVE 3rd-party RAM and re-install factory RAM.
Does that change anything?

 

[dawindmg08]

I agree with chrfr. The very first thing to do:
REMOVE 3rd-party RAM and re-install factory RAM. Does that change anything?

LOL, of course it would help if I hadn't sold the Apple RAM after I upgraded with OWC sticks.

I did pull al the sticks out and rearrange them last night; got a flicker of response from the iMac (it said it was updating) before it went to business as usual.

*UPDATE* -- I ran Carbon Copy Cloner last night to back up the whole drive in anticipation of taking it in to get serviced On a whim, I booted my MacBook Pro off of the SSD that I copied everything to -- and it WORKED. So that would imply the System folder is intact, and it's definitely a hardware issue with the iMac, no?
[doublepost=1552328479][/doublepost]*UPDATE PART DEUX - THE PLOT THICKENS*

I did a tech support chat with OWC and they had me pull two sticks out. The iMac started to boot and gave me a progress bar... then went to the circle with a slash. I had tried earlier to reinstall Mojave and it had crashed so I thought maybe the system was damaged (though it did boot from that external drive).

Anyway I just got another OSX drive to boot it and now I'm running disk first aid again, though I doubt it will find anything. I can try reinstalling Mojave but I'm not sure that's the issue here, and I'm scared to overwrite the OS if that's not the actual issue...

 

[chrfr]

I did a tech support chat with OWC and they had me pull two sticks out. The iMac started to boot and gave me a progress bar... then went to the circle with a slash. I had tried earlier to reinstall Mojave and it had crashed so I thought maybe the system was damaged (though it did boot from that external drive).

Anyway I just got another OSX drive to boot it and now I'm running disk first aid again, though I doubt it will find anything. I can try reinstalling Mojave but I'm not sure that's the issue here, and I'm scared to overwrite the OS if that's not the actual issue...

It sounds like you do indeed have defective RAM. I would not expect the computer to boot if it crashed partway through an upgrade/installation. Since you have a clone of the disk now, there's no risk in trying to reinstall Mojave.

 

[dawindmg08]

...Since you have a clone of the disk now, there's no risk in trying to reinstall Mojave.

Agreed, just tried it. The installer got almost to the end and then the iMac rebooted (probably a kernel panic) and went back to the Apple again with stalled progress bar.

At this point I gotta take it in cuz I don't have any Apple sticks to test in it. Some seriously bad juju.

 

[chrfr]

Agreed, just tried it. The installer got almost to the end and then the iMac rebooted (probably a kernel panic) and went back to the Apple again with stalled progress bar.

At this point I gotta take it in cuz I don't have any Apple sticks to test in it. Some seriously bad juju.

Apple will probably give you some hassle about testing with 3rd party RAM installed. Is there no combination of modules you can use to get the computer to work? I don't know that the computer requires the RAM to be installed in pairs so you might try them separately.

 

[akidd]

Sorry not to be any help but it is an intriguing thread. Best of luck with getting it up and running again.

 

[dawindmg08]

Apple will probably give you some hassle about testing with 3rd party RAM installed. Is there no combination of modules you can use to get the computer to work? I don't know that the computer requires the RAM to be installed in pairs so you might try them separately.

If I have time I will try inserting the sticks one at a time. Luckily I'm taking it into an Authorized service place so I'm less-likely to get grief over the OWC RAM.

If they test the RAM and it's faulty, I'm actually in a bit of a pickle because I'll have to wait for them to ship me replacement sticks and I don't have the original Apple sticks to put back in. Maybe the repair place will give me a "loaner" stick, LOL

 

[dawindmg08]

*SOLVED*
Defective RAM. Tech swapped out the sticks and it booted up normally. Picking it up tomorrow. FYI it was still covered under AppleCare, even with 3rd-part memory. Now I gotta get the RAM replaced; at some point I'll spring for a couple sticks from Crucial or another vendor to have on hand for when it fails next. Never buying from OWC again.

 

[SaSaSushi]

Glad you confirmed the issue.

I've got zero experience with OWC but I do recommend Crucial very highly. Crucial is the consumer division of Micron, the maker of the RAM most iMacs ship with from Apple.

I've had only good experiences with Crucial.