Late 2010 iMac getting quarter way through booting then turning off
Ok - first things first, apologies for a long post - I have lots of details about this issue.
As far as I can remember, about a couple of weeks ago I was working on my iMac (Late 2010, I believe running High Sierra) and it got stuck and froze (the spinning rainbow wheel of doom).
I waited for about 5 minutes then force shut down the iMac using the Power button. From there, the iMac simply refused to start up. It would get halfway through a very slow boot up - i.e. loading bar gets halfway - then simply turn off and die.
Here is what I have tried, and the various results for each:
Safe Mode - I attempted to boot into Safe Mode by holding shift when I turned the computer on. Unfortunately it simply doesn't get to Safe Mode, the iMac turns off half way.
Recovery Mode - I attempted to boot into Recovery Mode by holding Cmd + R and succeeded, but when I attempted to perform first-aid on the drive, I got this:
Booting into a different drive - I only have the recovery drive separate, so same result as (2).
Performed Apple Diagnostics (on my iMac known as Apple Hardware Test) by holding D on startup. I ended up with error code -3403D.
Reset NVRAM multiple times by pressing Option + Cmd + P + R - no change.
Reset SMC multiple times by unplugging. No change.
Booted into Verbose Mode - everything went smoothly until it got to checking the Catalog File, where it stopped, before spewing an error message and shutting down after 3 seconds.
Booted into Single Boot Mode by holding Cmd + S on startup and typing
fsck -fy. I repeated this over and over but it didn't say anything different, just that the drive couldn't be verified completely.
I'm aware there may be ways to fix this by reinstalling MacOS. I'm also aware that this could be a hard drive issue, however, I'd like to exhaust all other options before I consider that. Are there any other ways anybody knows hot to fix this?
I'd like to note that now, a few weeks after the initial issue the iMac only makes it quarter way through the boot before turning off.
I'd also like to note that I have seen these websites:
But nothing has worked. Can the Apple Stack Exchange Community help me better?