INSTL_ERR12 Hardware Thoughts

Unless you have an extended warranty with the vehicle, Ford will not replace a 2018 APIM under warranty.

You can check the hub part number and compare it here to see if your hub is CP compatible.
Media Hub, CarPlay Compatible - 2015-2020 Ford/Lincoln - SYNC 3 - Ford / Information - CyanLabs Official Community

2018, not surprising…have you identified the unit model using the Syn3 Updater interrogator log?

A master reset will wipe all phones and BT connections on the Sync unit by design. If it is restoring the devices, you found your problem.

Not good.
As for the second part, it looks like file (eMMC) corruption and/or storage controller failure or corruption. This is not repairable in normal circumstances.

You’ll need get past the security to be able to do that, and then have signed packages for install.

Sure, but your leaving a big hole in your vehicle integration that the Maestro will not fill. Many systems will have issues you will never solve. Just ask the guys with the big screens…

Sure sign this is a hacked or failing unit.

Well, I think the APIM is a replacement or upgraded unit from China that is flashed with incompatible software. There are many of these out there, unfortunately, and we have dealt with many also. These are the exact symptoms of those units, in different combinations. Or you have an APIM that has failed in a similar way. Either way, just replace the unit and be done with it. You will spend more money trying to fix this than buying a legit replacement.