I've got an iMac, which is doing a restart loop, just a white screen and a chime going in a loop

Jenaraj Jen
Jenaraj Jen used Ask the Experts™
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Hi All,

I've got an iMac, which is doing a restart loop, just a white screen and a chime going in a loop.... the screen doesn't go blank when it restarts, stays white and you keep hearing the chime every 2 to 3 seconds, I've tried all the normal fixes, like holding the shift key, pressing command-option-r-p... nothing seems to work, would anyone know a fix?

I know last resort is taking it to Apple but the machine isn't covered by Apple Care...


Thanks
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bbaoIT Consultant

Commented:
please try entering Recovery Mode to troubleshoot further.

just hold down Command-R or one of the other macOS Recovery key combinations on your keyboard immediately after pressing the power button to turn on your Mac, or immediately after your Mac begins to restart.

https://support.apple.com/en-au/HT201314
Jenaraj JenIT Systems Engineer

Author

Commented:
hi BBAO,

I've tried that, ive tried most things...

thanks :)
bbaoIT Consultant

Commented:
have you tried first resetting NVRAM, PRAM, and SMC followed by entering recovery mode?

FYI -
https://www.macworld.com/article/2881177/macs/how-to-reset-your-macs-nvram-pram-and-smc.html
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Commented:
Sounds like a bad boot sector from the chosen boot device.

Have you also tried holding down the Option key right after boot to see if you can see other boot devices or the recovery partition?
Jenaraj JenIT Systems Engineer

Author

Commented:
HI Owen,

yes I have, but nothing happened.
If holding down the option key during boot does not bring up the menu with disks to select, then your disk is dead and needs to be replaced.  If you need to recover data, it's time to send it out to data recovery experts.
Jenaraj JenIT Systems Engineer

Author

Commented:
the mac is dead, powersurge.
IT Systems Engineer
Commented:
the mac is dead, powersurge.

Commented:
Thanks serialband, that would have been my next comment. That drive or the circuits that read the drive might  be dead.  

If you have another Mac around, you can open the bottom of your computer and remove the drive. Mount it in an external USB case and attach to another Mac to see if the drive is readable. If it is, the mother board has been damaged. If not, the computer MAY work with a new drive, but no telling what else may have been damaged inside.
bbaoIT Consultant

Commented:
actually you can simply attach a known bootable USB stick drive with OSX or macOS installer on it, then boot the Mac with Option key held, you should be able to see the options to start the Mac from the external USB drive. you may run Disk Utility to check the internal drive once started.

Commented:
I like bbao's suggstion, except if nothing else shows up on an Option start, then I am fairly sure the disk is dead. Unlikely both partitions (system and recovery)  got corrupted at the same time. Possible, but highly unlikely.

That said, if you do not care what is on the machine, boot from a USB device, try formatting the internal drive, and see if it can work. If that fails, the drive is dead.

BUT, if you can boot from a USB stick, the computer is most likely good. I am not convinced that the computer itself is dead.

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