iMac 2015 won’t boot past progress bar

[d_gomaiste]

Hey guys,

Today, my iMac (late 2015, 21.5”, 8GB RAM) has unfortunately been stuck in a boot loop and nothing seems to be fixing it. It seemed to be working fine last night prior to shutting down, albeit a little slow.

I’ve tried multiple PRAM/SMC resets, using repair disk in recovery mode, and the Apple Hardware Test. I cannot boot into safe mode, and verbose mode only works very briefly before sending me to the same hanging startup screen.

Repair Disk and the AHT both report everything to be in good working order.

Interestingly, the progress bar will get to around 75% before it suddenly changes to a white block and freezes there. Here’s a picture of this: https://imgur.com/gallery/P4L8JxY

Any ideas as to what’s going on here and/or other ways to diagnose the problem? Really hoping this isn’t a failing GPU.

Thanks!!

 

[casperes1996]

Have you tried just reinstalling macOS?

 

[d_gomaiste]

I’m doing that right now, will report back once it’s done!

If that doesn’t help, is there anything else I should look into?

I really don’t want to buy a new Mac — I just bought this one last year, but it was unfortunately not eligible for Apple Care as it was an open box deal from Best Buy.

 

[d_gomaiste]

Just reinstalled OS X (10.11.6) and it doesn’t seem to have fixed the issue.

I let it reinstall while I ran some errands, and when I came home, the login screen was actually up. However, I was unable to login — it hung for a bit after I entered my password and then gave me a black screen.

Upon restarting, I’m having the same issue pictured in my first post.

Any suggestions welcome!! Thanks so much!!

 

[casperes1996]

Just reinstalled OS X (10.11.6) and it doesn’t seem to have fixed the issue.

I let it reinstall while I ran some errands, and when I came home, the login screen was actually up. However, I was unable to login — it hung for a bit after I entered my password and then gave me a black screen.

Upon restarting, I’m having the same issue pictured in my first post.

Any suggestions welcome!! Thanks so much!!

Do you have an external hard drive you can try installing to, to see if it's a problem with the hard drive or something else?

 

[Fishrrman]

I second casperes' suggestion to do an OS install onto an external drive, and see if you can get that set up as a "secondary boot drive" -- bootable to the finder.
You can even use a USB flash drive (16gb or larger) if you don't have a spare hard drive -- it will work, too.

IF you can boot externally without problems, but CAN'T boot from the internal, it points to the drive as the source of the problem. It could be a software-related problem, or hardware-related.

IF you come to the conclusion that it IS the drive, you might consider just "leaving it be" if you don't want to pay to replace it or don't want to take the risk of doing it yourself.

The solution would be to buy an external USB3 SSD, plug that in and set it up to become the boot/run drive. This isn't hard to do and (assuming the internal is a platter-based HDD) you'll be amazed at how much BETTER it runs with an external USB3 SSD...

 

[d_gomaiste]

Thanks so much for the suggestions @Fishrrman and @casperes1996

To create a bootable USB drive, would I be doing this from recovery mode?

 

[Fishrrman]

"To create a bootable USB drive, would I be doing this from recovery mode?"

Yes, that can work.
Give it a try.