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:
Chassis
...
Automatic Transmission
Release the parking brake.
Start the engine.
Shift to D, then to N.
Turn off the engine.
Leave the ignition switch in ACCESSORY (I) so the steering wheel does not
...
Main Valve Body Disassembly, Inspection, and Reassembly (A/T)
Clean all parts thoroughly in solvent, and dry them with compressed air.
Blow out all passages.
Do not use a magnet to remove the check balls, it may magnetize the check
balls. ...