Sorry for late response but I was busy the last time.

The black screen came after a period of time not after an update, the gps was long time before that updated.
I have tried to update again but the last update is still from 2012 so it's not updating. I have already updated with that update previously
Seems like the gps module is the problem, that's what they told me (kenwood authorized service center) , fixing it will be around 300 euros

I have tried to do what catymag said but I can't even take the unit out, the car was bought with the unit and I don't have the metal pieces to take it out.

Many thanks for your answers