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:
Map Coverage
The navigation system provides map
coverage for the contiguous United States,
Alaska, Hawaii, Canada, and Puerto Rico.
The map coverage consists of accurately
mapped (verified) metropolitan area ...
Place Phone Number
DEST button
►DEST Menu 2►Place Phone Number
Select a destination by phone number. Only phone numbers in the database are
recognized.
1. Enter the area code and phone
number. Select ...
GPS System
The signals received from the GPS satellites
are extremely weak (less than a millionth
of the strength of a local FM station) and
require an unobstructed view of the sky.
The GPS antenna is loca ...