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:
Cable Reel Replacement
Removal
Make sure the front wheels are aligned straight ahead.
Do the battery terminal disconnection procedure,
then wait at least 3 minutes before starting work.
...
Map, Voice, Entering Destinations
...
Installation
Hold the gearbox housing using a C-clamp (A) and wooden blocks (B) to a
workbench as shown. Do not clamp the cylinder part of the gearbox housing in
a vise.
...