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:
Rocker Arm Assembly Installation
If the rocker arm assembly is disassembled, reassemble the rocker arm
assembly.
Apply engine oil to the end of the valve stem.
Install the rocker arm assembly.
...
Guidance Menu
MAP MENU (on map)
►Guidance Menu
Display the guidance points and freeway exits for your route, and set the
display
mode for the map and guidance screens.
Select an item.
The following ...
HFL Menus
The ignition switch must be in ACCESSORY
or ON
to use HFL.
To use HFL, you must first pair your Bluetooth-compatible cell phone to the
system while the vehicle is parked.
Phone Setup
...