Here's how to unlock the userspace login prompt and the recovery TftpServer, once you have a SerialPort attached and have managed to UnlockTheConsole:

At the U-Boot console, type:

  setenv shadow_data admin:XkRnx5gdf6RdQ:0:0:99999:7:::
  setenv sync_to_pt enable
  reset

This will boot the device with the protected admin password permanently reset to 'admin'.