What happens when you try to raise the glass? There is a weakness with these that the actual mechanism fails, so the motor is turning, but the glass goes nowhere.
Also, there are a lot of sensors which may stop the motor from getting power. Additionally if the control unit has failed, that may stop the motor getting power.
If it were me, I'd do some testing to absolutely ensure that the motor is getting power, and has failed. Then you'll have to try and find a replacement by comparing with others available. The motor alone is not available from Maserati / Eurospares.
Then you'll need to see if the motor can actually be replaced from the mechanism.
If all that works out, let us know what motor you find fits?
Cheers
C