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:
Handling the Unexpected
This chapter explains how to handle unexpected troubles. ...
Adding a Waypoint
(“Pit Stop”)
You can add up to four waypoints along
your route.
1 Press the DEST button.
2 Select Waypoint.
3 Select search method.
When you select Places Around the
Waypoint, select the desired waypoint.
...
Controls
This chapter explains how to operate the various controls necessary for
driving. ...