I found this...

To resolve the white screen issue on your unit, please follow the steps below:

1. Connect Navman GPS to PC via mini-USB cable.
2. Go to ‘Start’
3. Go to ‘My Computer’
4. Open the Navman Unit
5. Open the ‘Navman’ folder
6. Open the ‘Database’ folder
7. Delete the following file only - ‘database.db’
8. Close the folders
9. Disconnect the mini-USB cable then restart the Navman GPS by sliding the switch to ‘Restart’ then back to ‘On’ after 10 seconds

Please Note: The database.db file will be generated automatically once the folder is closed.

Good Luck...
November 2016