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:
Driver's Seat Position Sensor Replacement
Removal
NOTE: Do not turn the ignition switch to ON (II), and do not connect the
battery cable while removing the driver's seat position sensor.
Do the battery terminal disconnection ...
Body
...
Controls Near the Steering Wheel
*1 : To use the horn, press the center pad of the steering wheel.
*2 : If equipped. ...