infinite reboot after update (high sierra) imac 27 mid 2010

[ZenSurfeur]

Hi from France
I really got a big problem on an iMac27" mid 2010 High Sierra 10.3.6 (i7 2,93Ghz, 8Go ram, Hd6970 2Go, HDD 1To) after an update... infinite reboot at about 3/4 of the progressing bar
I tried :
- 1 - smc and nvram/pram > no effect
- 2 - safe mode > no effect, infinite reboot
- 3 - recovery from partition (cmd + R) > no effect, infintie reboot
- 4 - internet recovery (shift + command + alt + R) > no effect, infinite reboot
- 5 - Apple Hardware Test (cmd + D) ethernet wired > no effect, error -3403D
- 6 - swap with an SSD high sierra updated from an imac 27 mid 2011 > no effect, infinite reboot
- 7 - all points from 1 to 5 with the ssd > no effect, infinite reboot
- 8 - put a NEW CR2032 cell battery, all points form 1 to 5 > no effect, infinite reboot

Any idea?
Thx, take care

 

[Azrael9]

Hello ZenSurfeur,

Same boat here with iMac 27 inch late 2012 Moutain Lion was the OS it shipped with, I think.

SMC, NVRAM/PRAM no effect.
Safe mode. Infinite.
Recovery over the internet. Hangs.
Apple hardware diagnostic test. No errors. Mainboard fine. Hard drive fine. Memory fine. Says I'm fine.
Use the Terminal. Hard drive came back fine.
Tried Terminal command line boot. Hangs.
Have external SSD with High Sierra. That won't boot either.

(See my thread re: similar issues.)

Hopefully something has the golden keys.

Regards,

Azrael.

PS. I wonder, could the gpu be cooked or the drivers borked? Can't access disk utilties to try further diagnostic.

 

[Azrael9]

ZenSurfer.

There was 'ONE' thing that came up during my Internet sleuthing.

'Battery.' Allegedly, the 2011 iMacs came with a battery (they're good for 5-ish years...) and when they run out they can affect booting. The user in question took apart their iMac and it solved the boot problem after some careful gymnastics to get at the battery.

I'm not sure if this would apply to your or my 2012 iMac.

I DO remember my 1997 Mac PPC Clone had a battery for Date and Time. When it died? My Mac would 'not' boot.

Food for thought. Anyone?

Azrael.

 

[ZenSurfeur]

post updated

 

[nambuccaheadsau]

The error code indicates yourn iMac cannot run Diagnostics as it is a little too old. Go to the Github link and download the correct Apple Hardware Test version for your iMac, model 11.3, and copy it to a thumb drive. Boot from that and run the full test.

GitHub - upekkha/AppleHardwareTest: Apple Hardware Test Download Links

Apple Hardware Test Download Links. Contribute to upekkha/AppleHardwareTest development by creating an account on GitHub.

github.com

 

[ZenSurfeur]

I think this update makes some damages I mean i could use the AHT before, maybe some corrupted files, a wrong date...

 

[Azrael9]

i tried the diagnostic test in my iMac. It said my hardware is fine.

Still hangs on boot.

Azrael.

 

[ZenSurfeur]

i tried the diagnostic test in my iMac. It said my hardware is fine.

Still hangs on boot.

Azrael.

with a usb stick of AHT ?