On daughters 06 Grande Punto the starter wouldn't work and the fuel pump, they were both run off the same relay at fusebox, supply to activate relay was duff. Wire rotted through inside the plastic sheathing at ECU plug. If able to power up the correct relay may be worth checking.
If it won't turn over, then check that there is power at the starter.
If the big red cable on the starter gives you "12v" when you put a voltmeter across it, then it is powered. Next connect the small tab on the starter motor (it should have a small wire from the starter already attached to it) directly to the positive post on the battery. You'll need quite a thick wire and don't get anything caught in the machinery.
If it activates the starter solenoid then the starter is good. If it doesn't activate the starter solenoid, then the problem is the starter solenoid.
If the starter/solenoid are good, then the problem is it doesn't know when to crank. Locate the starter relay and fuse and make sure they're all good. If you've had the fuel pump/relays apart then there's potential for something to be disturbed/missing.