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Big Sur and now bricked iMac late-2015

S

sheirah

macrumors newbie
Original poster
Dec 16, 2020
2
0
Hi guys,

I went against my usual practice of upgrading to a new OS without waiting a while before doing so and now I have a bricked iMac.

I bought a new iPhone and iTunes wasn't letting me back my current phone up and tech support told me it was likely because I needed to upgrade to Big Sur. Ok, I was frustrated enough that I did it and now wish I hadn't.

This morning my computer randomly restarted twice and didn't turn back on after the third time the screen went blank. Apple support tried walking me through a CMD + R reset but nothing we did worked. My computer is now a black screen with no inclination of ever turning back on again.

Anybody have this issue? Does it sound like something caused by Big Sur (I installed it one day ago). Never, ever had an issue with the Mac until this, as I'm a very light user and have taken great care of it since I got it.

Anything to be aware of before I take it into my appointment at the Genius Bar? I'm preparing for the worst, I suppose, and would appreciate any advice.
 
Did they try Internet Recovery "Option+CMD+R", as well as CMD+R, there's other shortcut variations too, in case you didn't try these already.

Mac startup key combinations - Apple Support

Learn about the Mac features and tools that you can access by holding down one or more keys during startup.
support.apple.com support.apple.com

Do you have another Mac roughly from the same era lying around for Target Disk Mode?
- Tether them with a Thunderbolt/Firewire cable, restart the other mac holding down T and restart your mac holding down Option, select the other mac's hard drive and see if you can boot into it. The OS on there must be compatible with your mac - so probably El Capitan upto Big Sur if memory serves.

Alternatively, do you have a bootable backup, made with Carbon Copy Cloner or Super Duper on an external drive - maybe not - but if so you could try booting from that. I'm assuming not as you'd have probably tried this.
 
I woke up recently to find my iMac 5K , late 2015, bricked
The internal 2TB HDD is not seen/recognised by the computer, only the 128GB SSD
All my computer does now is show the apple.com/startup web address when I try to boot
Im assuming the HDD has simply died though and that it isnt Big Sur
 
Hi barry6574,

read your post... did you manage to recover from the bricked situation?

i am hesitant to go past Catalina 10.15.6 as I had to restore at 10.15.7 and never upgraded ever since.

thanks
 
possibly SMC reset and CMD Option P + R. But could be the SMC. Advice is found on Apple Support website. However it's simple enough with that iMac. I have the same one. Remove all connected external devices. Remove the power cord from the iMac and let it simmer without power for 20 seconds or 30 seconds. Insert power cord. Wait 20 seconds or so. Turn the iMac on.

Also, take out the RAM and reseat them.

As user @Barry6574 hinted at. Could be a dead drive too. If your iMac doesn't make a sound - no immediate noise then probably a goner.

Good luck
 
sheirah said:
Hi guys,

I went against my usual practice of upgrading to a new OS without waiting a while before doing so and now I have a bricked iMac.

I bought a new iPhone and iTunes wasn't letting me back my current phone up and tech support told me it was likely because I needed to upgrade to Big Sur. Ok, I was frustrated enough that I did it and now wish I hadn't.

This morning my computer randomly restarted twice and didn't turn back on after the third time the screen went blank. Apple support tried walking me through a CMD + R reset but nothing we did worked. My computer is now a black screen with no inclination of ever turning back on again.

Anybody have this issue? Does it sound like something caused by Big Sur (I installed it one day ago). Never, ever had an issue with the Mac until this, as I'm a very light user and have taken great care of it since I got it.

Anything to be aware of before I take it into my appointment at the Genius Bar? I'm preparing for the worst, I suppose, and would appreciate any advice.
Click to expand...
Update: Had to pay $700 to have the logic board replaced and then it worked.
 
bazzler said:
I have not
Click to expand...
I do not think late 2015 iMac is compatible at all with Big Sur.
I have twice tried to upgrade and resulted only to crashes eventually after a few weeks or weird things happening.
Sticking with Catalina now!

iMac (Retina 5K, 27-inch, Late 2015 4 GHz Quad-Core Intel Core i7 16 GB 1867 MHz DDR3
 
Jeffchoa said:
I do not think late 2015 iMac is compatible at all with Big Sur.
I have twice tried to upgrade and resulted only to crashes eventually after a few weeks or weird things happening.
Sticking with Catalina now!

iMac (Retina 5K, 27-inch, Late 2015 4 GHz Quad-Core Intel Core i7 16 GB 1867 MHz DDR3
Click to expand...
Did you do any recent upgrades of RAM before installing Big Sur? I'm thinking about trying again. I had upgraded to Big Sur but at the exact same time I had installed 4X8 gb of aftermarket RAM (32 gb total); and I thought it was the OS so I went back to Catalina. I still had the crashes and kernel panics. So, I took out the aftermarket RAM and put back the original 8 gb and no more crashes for days. I'm on Catalina again and want to put Big Sur back on hoping for no crashes.
 
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Bricked mine as well. Retina 5K, 27-inch, Late 2015 4 GHz Quad-Core Intel Core i7 16 GB 1867 MHz DDR3
Sticking with Catalina for now. 32 GB RAM and plenty of space (350 GB on the HDD) but just a complete no go. To obvious seemingly to be planned obsolescence? They sold a BUNCH of these machines
 
I have an
iMac (Retina 5K, 27-inch, Late 2015)
4 GHz Quad-Core Intel Core i7
32 GB 1867 MHz DDR3
1 TB SSD
Have been running Big Sur since its release and 11.6 since its release and have had no problems whatsoever.
 
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jlt3 said:
Bricked mine as well. Retina 5K, 27-inch, Late 2015 4 GHz Quad-Core Intel Core i7 16 GB 1867 MHz DDR3
Sticking with Catalina for now. 32 GB RAM and plenty of space (350 GB on the HDD) but just a complete no go. To obvious seemingly to be planned obsolescence? They sold a BUNCH of these machine
Click to expand...
jlt3 said:
Bricked mine as well. Retina 5K, 27-inch, Late 2015 4 GHz Quad-Core Intel Core i7 16 GB 1867 MHz DDR3
Sticking with Catalina for now. 32 GB RAM and plenty of space (350 GB on the HDD) but just a complete no go. To obvious seemingly to be planned obsolescence? They sold a BUNCH of these machines
Click to expand...
Big Sur is nice. I’m probably not even trying Monterrey. Big Sur is enough. I had issues/kernel panics/quick & consistent crashes with no commonality with a aftermarket ram upgrade. Memtest86 showed no issues. But I had a gut feeling it was the ram. So I bought Crucial’s sticks and used with original 2x4 8gb, absolutely no issues. It was like I had a new computer. Big Sur is worth the fight. The brand of ram is important. Timetec was a waste of money.
 
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It may well the memory, I had issues with Other World Computing's memory crashing my machine in 2019 from RAM bout in 2017. Returned all 4 modules and received replacements that worked... up until Big Sur anyway. Wonder if that's still covered or even if issue is able to be proved or demonstrated.
 
OWC will take back memory for exchange if you persistent enough. They certainly can't test it like you can with memtest86 plugged into a Mac.
 
Last edited:
Ouch, $700 to fix a 2015 Mac? I would have put that towards a new Mac like an M1 Mini or another iMac. But first I would have escalated my concerns up to mgmt because it was working fine up until Big Sur. I would have tried to get the $700 charge reduced or waived.
 
HardyCE said:
Big Sur is nice. I’m probably not even trying Monterrey. Big Sur is enough. I had issues/kernel panics/quick & consistent crashes with no commonality with a aftermarket ram upgrade. Memtest86 showed no issues. But I had a gut feeling it was the ram. So I bought Crucial’s sticks and used with original 2x4 8gb, absolutely no issues. It was like I had a new computer. Big Sur is worth the fight. The brand of ram is important. Timetec was a waste of money.
Click to expand...
I had an issue with aftermarket RAM, but with Catalina. Got it changed for no charge from the approved Apple reseller I purchased the RAM from.
 
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