MacOS Catalina: Install Slows and Errors on MacBook Pro (13-inch Mid 2012)

For around 6 months I had intermittent issues with my MacBook Pro (13-inch Mid 2012) where it was randomly ending up on the folder with a question mark icon, or the no-entry icon.

It used a 250GB Samsung 840 SSD – which I had installed in 2014 – and I figured it must have finally been at its end-of-life.

I've replaced it with a 1TB Crucial MX500 SSD; the swap went smoothly and as expected.

Now, I'm having problems installing macOS Catalina at all.

After installing the new drive I did the following steps:

1. Downloaded the latest macOS Catalina from the App Store on my iMac
2. Created a new Catalina Install drive using Terminal createinstallmedia
3. Booted from the USB on the MacBook Pro
4. Formatted the drive to APFS in DiskUtility
5. Used the macOS install button, accepting terms etc..

The installer gets to around 50% normally (in around 5 minutes), but then it slows down dramatically, with the estimated time floating around 5-7 minutes constantly. The loading bar continues to move incredibly slowly (using the ol' cursor on the boundary of the loaded section to track progress).

This goes on for well over an hour, and at around 70% it fails with the error:

An error occurred while preparing the installation. Try running this application again.

I've taken the following troubleshooting steps so far:

1. Reset SMC
2. Reset NVRAM, PRAM
3. Recreated the install USB pendrive
4. Re-recreated the install usb on another USB pendrive
5. Used different USB ports
6. Online-recovery (defaults to Mountain Lion, which got all the way through the progress bar then loads to a folder with a question mark at mid-install auto-reboot)
7. Cloning the old Samsung SSD to the new Crucial SSD in DiskUtility
8. Numerous power-cycles, and letting the machine sit for a bit etc.
9. Run health-checks on the old and new SSDs, both return no issues

The machine had otherwise been running great. Fast as always with no known issues with RAM, or battery life, etc.. I can't think of what else to try at this point.

The machine's also in near-new condition, it's been very well looked after. All the ports etc are clean and in good working order, as are the charge cables.

There are no Apple stores or authorised repair centres where I live (boat/flight required for the closest, which isn't an option due to Covid lockdown).

Any ideas on what to try next would be greatly appreciated, I'd very much like to see this MacBook working again.

Many Thanks

Craig