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:
Reassembly
Install the upper spring seat (A) to the upper spring seat clip (B).
NOTE: Make sure to securely set the upper spring seat to the hook (C) on
the spring seat clip.
...
EPS Control Unit Removal/Installation
Do the battery terminal disconnection procedure.
Remove the under-dash fuse/relay box.
Disconnect EPS control unit connector A (11P) and connector B (16P) by
pus ...