Are you using the cable that came with the 51?

There could be a problem with the cable.

There is no need to turn on the car just turn the key so there is power to the 51

What happens when you you take it off the cable and turn it on?

Have you stopped the route by the "X" and put the favorite back in as a new route.

Are you connected to the Garmin app on your phone if so turn it off.

Turn off Bluetooth on the 51 if it is on. If it came with Bluetooth.

Turn off he 51 for 5 mins and then back on.

But with out the cable connected....

The other problem could be the spelling of the place you want to go in France.

I think you have it in English your 51 and are trying to add a French village and that can make problems.

The other thing is you just got the 51 did you use Garmin Express to update everything before starting out on your trip.

The first thing I do after I open the box is to connect to Garmin Express and do all the updates.

It is important.

As for the village you are trying to find I would use your phone a google it for the correct spelling in French.

It goes the same for streets in France.

I know I have been there many times and before I set out on my trip I add all the places I want to go and add them to my screen.
I even test all my saved trips just to make sure they work and show the correct location I want to go to.
Then I just have to pick that location and the GPS Calculators the distance.