Keeping the camera for a month unused is not a problem.
But whatever caused this, it sure does sound like there is something that needs putting right inside the body. Probably not a difficult repair, but it has to be done by someone who knows his way in the inside of the camera. And it probably will not be cheap.
Thanks Q.G.. Tomorrow I will test again my camera and after I will contact my supplier’s lab. I will keep you informed about the technical solution ... probably in a month from now. Thanks again