Bravetti Chopper Model FP 105H

Not positive as to your problem, but I was just given one of these and thought it didn't work. On closer inspection, I found a little switch that needs to be depressed from the bottom side. When I pressed it with a tiny screwdriver while holding down the bar on top, the motor runs!

I just have the white top with the motor and the glass jar thing. So I'm on a search for whatever is supposed to fit between them. There's room for a seal between the two, and I imagine it has something to push the tiny button, to activate the motor (guess technically it's a safety interlock).

In case it isn't obvious where that button is, turn the motorized plastic top upside down and look at the center. There's the star drive in the middle, and four little depressions, or holes around it. One of them isn't white inside. It's the magic switch! When I push it with a screwdriver and push the power bar, the thing comes to life...

If that works it for you, then your new mission is to figure out what pushes that button and put it in the right place.