Mid-2012 i7 Macbook Pro Dead. Will Not Install OS. Help :(

I was working as usual on my MBP last week, when it froze. This has happened upon occasion before, and was always just a case of holding down the power button and restarting. However, on this occasion, upon restarting I got the dreaded "prohibited sign" from then on.

I began troubleshooting and trying anything I could find online:

• Repetitively tried SMC, PRAM, NVRAM resets.
• Ran Disk Utility from Recovery Mode and attempted to repair the internal drive. Initially it allowed me to repair the main drive, but when I clicked "show all devices" etc and tried to repair the container volume, it always failed.
• I tried various Terminal related options, running Disk Repairs via Terminal etc
• I tried Target Disk, but unfortunately despite ordering both Firewire and Thunderbolt cables, my other older MBP can not run a compatible OS to interface with my broken MBP's disk.
• SATA Cable. I've been struck before by the infamous 2012 MBP HD SATA cable issue. I successfully replaced it a few years ago. When I replaced the SATA cable previously, I made sure to insulate it nicely with some electrical tape, to try to prevent it happening again in future. Upon examining the cable, it looked pretty pristine. To be on the safe side, I tried swapping the SATA cable of my older working 2009 MBP. Again, the same issue, the Prohibited Symbol upon start up.
• Via Terminal, I accessed trial versions of iBoysoft & Disk Drill software to scan and recover my internal HD. Neither worked. Stuck at "prepare scan" for up to 4 or 5 hours with no progress. Both seem to stick on a pre-scan preparation - and not scan any files for recovery.
• At this stage, I just wanted a working MBP because I use this for work, and I am now days behind schedule, working with the machine for hours each and every day. So I went for destructive methods. I had the idea in the back of my mind that although the disk will be formatted, I can attempt to run the file recovery software when I get the machine back up and running, to see if it can find any files from pre-format. I do have a backup of work files, but it is almost a year old, and there is some current files I frequently reuse that I would really like to have back - asides from the usual sentimental stuff of family photos etc.
• So I then started erasing the internal disk completely. Formatted it as suggested on all tutorials online. Mac OS Extended Journaled, GUID partitioning. If I am understanding this correctly, when I do this, there is a partition made for the new OS installed which is a container disk volume in APFS, or are converted to so in the process of reinstallation?
• Once formatted, I always run First Aid again and make sure all is coming back clean and clear.
• I have attempted several times now to reinstall an OS on to the machine, each time it fails. Firstly, I did the standard recovery mode boot up, then from the Utilities menu offered, I clicked Install OS. After several long hours installing Mojave, it would always fail to install at around 90%
• I then attempted to reinstall Mojave again using a bootable USB drive using the dosdude Mojave Patcher. Again, this failed near the end of installation
• Finally, last night, I tried for a second time using Internet Recovery. I'd tried this in an earlier attempt, and again, as Mojave was approaching the end of installation after many long hours on my sub-par connection, it failed.
• I began using an Ethernet cable for direct connection to my router, to make sure that isn't a factor, as it seems to have been for some people.
• I reformatted and ran internet recovery one last time last night, and this time I used the command shortcut to reboot the mac to install the base level OS that it supposedly shipped with - which started a download for Mountain Lion. This actually gave me a glimmer of hope, as I really though installing the earliest version of OS onto a clean hard drive would work.
• I opened COMMAND+L to show installer log. It worked its way through installing just over 400 "Chunks". I checked on it occasionally while it did this. The last time I checked it was nearing the 400 mark. I think just before it reached there, I heard the MBP restart. All I seen on the screen was a prompt to install Mojave, again. Without knowing what else to do, I presumed this was part of the full re-install, and it was automatically updating, so I proceeded. Again, it towards the end of the progress bar, it failed.

Runs just fine in Recovery Mode when I open Safari on Terminal. Handles web browsing smoothly. Yet, I can't boot it up normally. I can't seem to re-install ANY OS, using ANY method - USB Boot, Internet Recovery, wifi, ethernet etc

Also looked into included turning Encryption off, turning SIP off, and running a bunch of other Terminal diagnostic tools. I should have listed the error messages but I have no method of copy/pasting on the broken machine. I saw some errors along the way in reference to Tree Nodes, I think it was an invalid B-Tree node size.

Thanks, Steve.