I don't know if the fans you replaced are working but would you mind to try to boot the unit with Braiins OS and enable the immersion mode? So that it would ignore the fan check and for testing purposes.

Take note you can boot Braiins OS on this unit without flashing it and to make sure that the fan is not the culprit.
Paste the kernel logs and system logs here after.

Also, check the fan terminal try to clean it with isopropyl alcohol use a brush to clean the fan terminals and let see if we can see some improvement.

I hope the fixture will arrive soon because you can check these 3 hashboards if they are already dead or working.