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macrumors newbie
Original poster
Nov 13, 2019
Hi, I am having a problem with my mid-2011 21" iMac. It's been running great for this 8 years and running the last supported OS X (High Sierra) this past 2 years with no problem, but suddenly it just restarted while I was using it a week ago and now in boot loops. Searched many forums but couldn't find any solution to fix it.

So I ran Apple Hardware Test and it gave an error report that there was problem with the HDD fan. So I tried to open it up but found all the three fans are running ok. So, I followed video instructions on Youtube to disassembly the HDD, the optical drive, the motherboard, well basically everything in there and clean it all from 8 year dust and put it all back together again. And ran Apple Hardware Test again and this time found no error with the hardware, then tried the extended test but also no error reported.

Tried to run it again but still in boot loops. Usually about 2/3 of the bar and then the screen goes without the apple logo and the progress bar and after a minute just rebooting.

So I tried macOS recovery, internet macOS recovery but after the progress bar almost complete it just goes the same but not rebooting.

Tried to boot from High Sierra bootable USB but ended up the like using the macOS recovery.

So after searching the internet, someone suggest to use verbose mode. I managed to get a screen capture of the last lines before it gets into boot loops.

Has anyone ever experience this too ? What is the problem and how can you fix this ? Thank you.
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