2017 iMac Fusion Drive Failure - SSD Upgrade

My 2017 iMac Fusion Drive went bad so I purchased a 2TB SSD upgrade kit from OWC.

After installing and formatting the SSD, I kept getting an error during the install of a fresh OS. Even restoring from a backup of TM would fail at the very end of the process. I started to think that maybe the PCIe drive might be the issue, since I didn’t break the Fusion Drive before the upgrade, so I upgraded it as well.

After installing the new PCIe drive, the OS install and TM backups seem to complete without issue, but after the install and restart, the progress bar always froze at about 25%, and kicked me back to recovery mode without any kind of error or notification.

This happened no matter what I did. I tried a fresh install of the OS from recovery mode, installing from a bootable flash drive, and restoring from a Time Machine backup. Each option completed without any errors or warnings, but the system still won’t actually boot.

I decided to reset the PRAM and create another Fusion Drive using Terminal, and now the progress bar does complete at start up (with a random screen flash that happens every time at about 75%) but the computer still boots back right back into recovery mode.

I ran a hardware test and it states there are no issues, but that’s clearly not the case. I’ve been at this for a couple months now and I’m completely out of ideas. I’ve love any advice the community might have, bc I’m not ready to give up on this machine just yet.

Thanks in advance for your help!