Finally I brought the cab at home to take pictures and it turns out that in fact there was just a problem of loose contact !
The kids could play with a few minutes but when I lift the screen game froze and no longer wanted to leave. Anyway, this is a minor problem, and then children want me to fix it in order to play with (they liked the simplicity of the game) .

So sorry but for now I keep the cab.

A picture of the screen with the actual bug :

Thanks Bruno for the relay !

More information : the cab doesn't work, the screen display many squares, appareance is good.

More pictures :











The machine is in France (near Lyon).