2018 4 in. sync 3 black after attempted upgrade and downgrade

You cannot go back to Sync 3.0 from Sync 3.3/3.4. However, you have 2 options:

  1. install an 8" screen. (Dependent on the APIM model and vehicle, this can be costly.)
  2. Load the 4" version of Sync 3.4. The latest available is NU5T-14G381-BB 424Mb Sync3 v3.4.22251 08.09.2022. You cannot use the Syn3 Updater, you will need to do this manually.

This will be the contents of your autoinstall.lst file:

[SYNCGen3.0_ALL_PRODUCT]
Item1 = NU5T-14G381-BB_1665526155000.TAR.GZ
Open1 = SyncMyRide\NU5T-14G381-BB_1665526155000.TAR.GZ
Options = AutoInstall

Place this file in the root of the USB driveā€¦
autoinstall.lst (148 Bytes)

Place the NU5T-14G381-BB file in the SyncMyRide folder on the USB drive.

Insert the USB drive in the car, the message should appear it is upgrading. It should take less than 15 minutes.

If the installation fails to load, you will likely need to remove Gracenotes to make room for Sync 3.4. You can do this with Syn3 Updater or following the tutorial.
Tutorial: Removal of Gracenotes - Ford / Guides - CyanLabs Official Community