For the fsimx8mp releases the new NBoot currently does not support a user interface to recover from a deleted or corrupted UBoot.
For that, we now provide a recovery tool to reflash the NBoot as well as the UBoot. The tool is ready to download as a zip archive on "My F&S" under
<Your-Board-Name> -> Linux -> Recovery Tool
In the same directory there exists a PDF document, which explains the steps necessary to recover the UBoot.
Your F&S Support Team