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jimmieb45

macrumors newbie
Original poster
Sep 25, 2021
9
2
Hi friends. I was upgrading to Ventura from Monterey 12.4 this morning and my power cut out. My 2019 27inch iMac is now bricked and only runs the fans at max speed after pressing the power button. No screen turn on, all black. I've attempted the usual power cycle, pram, smc, etc to no avail.

Two questions:
1. Is this the right thread for this question? If not, I'm sorry...please point me to the right spot!
2. Any ideas what could have gone wrong and how to fix? I've never seen a black screen with no audio tone or anything but maxed out fan speed. No logo from failed backlight nothing, just fans.

Thanks!
 
Sounds like the update might have been flashing firmware when the power cut out… bad luck indeed.

Maybe internet recovery still works, hold Cmd-R to see if it does. If not, send it in for repair.
 
Hi friends. I was upgrading to Ventura from Monterey 12.4 this morning and my power cut out. My 2019 27inch iMac is now bricked and only runs the fans at max speed after pressing the power button. No screen turn on, all black. I've attempted the usual power cycle, pram, smc, etc to no avail.

Two questions:
1. Is this the right thread for this question? If not, I'm sorry...please point me to the right spot!
2. Any ideas what could have gone wrong and how to fix? I've never seen a black screen with no audio tone or anything but maxed out fan speed. No logo from failed backlight nothing, just fans.

Thanks!
Sorry to hear about this happening. I hope you have your Mac backed up. Contact Apple and they will arrange for a appointment at store to do a DFU revive.
A revive updates the firmware and updates recoveryOS to the latest version. A revive is designed to not make any changes to the startup volume, the user’s data volume, or any other volumes. User data may be retained if recoverable.
if the data is backed up to a ASR volume using some backup program you can do a DFU restore (reset to factory defaults)
A restore updates the firmware, updates recoveryOS to the latest version, and erases and installs the latest version of macOS on your internal storage. When this process is complete, any data on any internal volumes is unrecoverable.
You must restore the firmware and erase the internal flash storage if:
  • Reviving the firmware is unsuccessful
  • You can’t start the Mac from the startup volume or the recoveryOS
 
if it's imac with T2 chip then it's unlikely you have bricked the firmware, otherwise it's very likely
 
if it's imac with T2 chip then it's unlikely you have bricked the firmware, otherwise it's very likely
The 2019 does not have a T2 chip as far as I am aware. This is so strange to me, I’ve had to power go out before but my mac runs completely fine then after. Why would upgrading to Ventura throw everything off?
 
Sorry to hear about this happening. I hope you have your Mac backed up. Contact Apple and they will arrange for a appointment at store to do a DFU revive.

if the data is backed up to a ASR volume using some backup program you can do a DFU restore (reset to factory defaults)
Thank you for the full reply. I was reading about DFU revives and restores. Do those only work on devices with a T2 chip? As far as I could tell they do and my 2019 iMac does not have one.

Earlier I tried to plug my MacBook in and run Apple Configurator and revive the iMac from there with no success :/

Maybe the Apple Store has a way to do the same thing…unsure. The last thing I want to do is replace hardware…at least I have a recent backup.
 
Thank you for the full reply. I was reading about DFU revives and restores. Do those only work on devices with a T2 chip? As far as I could tell they do and my 2019 iMac does not have one.

Earlier I tried to plug my MacBook in and run Apple Configurator and revive the iMac from there with no success :/

Maybe the Apple Store has a way to do the same thing…unsure. The last thing I want to do is replace hardware…at least I have a recent backup.
The DFU documentation says it requires a 2020 iMac that has a T2. So look at the below documentation instead

 
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Following up on this thread.

Apple support through the phone number you provided had me attempt boot in Internet Recovery mode (Cmd + Option + R), nothing happened. So they had me then make sure the memory in the back of my computer was set correctly, then try again.

Viola! Computer booted up in internet recovery mode. I then ran first aid on the hard drive, everything looked fine, restarted the computer from the IR menu, and I was back on 12.4 like it was before it crashed. All data the same.

Thank you all for all your help!
 
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