Never tried this as I don't have my Honda yet, but was researching the Honda Satnav system to see if I want it instead of my TomTom. This was a post from a guy who works for Honda:
The official Honda method for forcing sat-nav to reset to older disc is as follows:
1. Start the engine.
2. error message appears on screen with old disc inserted.
3. Push 'MENU' and 'ZOOM DOWN' switches simultaneously for 2 seconds.
4. Screen turns to SYSTEM LINK page with a fanfare.
5. Press 'NEXT' switch (opens car staus page).
6. Press 'NEXT' switch (opens yaw rate page).
7. Press 'NEXT' switch (opens diagnosis menu page).
8. Select 'UNIT CHECK'.
9. Select 'FORCE DOWN LOAD'.
System will now start to download the old operating system firmware from the old disc, showing progress on a green bar gauge.
When finished the unit should be able to be started normally.