Depending on the length of time the power was interrupted, your system may require GPS initialization.

If initialization is not necessary, the system proceeds directly to the Startup Confirmation screen.
If the system fails to locate a sufficient number of satellites to locate your position within 10 minutes, the following screen is displayed.

If you are experiencing GPS reception problems:
Sunvisor Removal/Installation
'9-10 models
Click here for an interactive version of this procedure.
NOTE:
Put on gloves to protect your hands.
Take care not to damage the sunvisor or the headliner.
...
Changing Your Destination
There are several methods you can use to change the route destination. ...
Fog Lights*
When the low beam headlights are on, turn
the fog light switch on to use the fog lights.
When the fog lights are on, the indicator in the
instrument panel will be on. ...