The City Navigator maps that were on the device before the update worked after the update.

After the update, putting in City Navigator maps, regardless of regions, would fail authentication. Applying gimgunlock+mapsig won't work. Temporary authentication method won't work either.

I downgraded the firmware back to version 2.00, and all City Navigator maps work fine now. You can check the Garmin firmware section here to get version 2.00 and another earlier version.