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:
Navigation—Changing Route or Destination
You can alter your route by adding waypoints to visit, adding streets to
avoid, or changing your destination during route guidance. ...
On-Screen Commands
The system accepts these commands on
any screen. There are over 100 on-screen
commands. Say what is written on the
screen to activate that selection. For lists,
you can say the list item number to ...
Instrument Panel Indicators
The instrument panel has many indicators that give you important information
about your vehicle.
Malfunction Indicator Lamp
Low Oil Pressure Indicator
The engine can be severely damaged if th ...