I found a similar picture, I guess the insulator is removed the small brown wire fitted the insulator replaced then the main cables attached to the end of the stud.
if you look at the big metal ring, it is soldered to the terminal stub on the solonoid which is the normal place on most other vehicles to attach the ignition (brown) wire Fiat have just done something slightly different.
However, by the sound of it, you may have tried starting the car with the ignition wire hanging loose and touching earth which means a main fuse may have popped hence the lack of any power.
if you look at the big metal ring, it is soldered to the terminal stub on the solonoid which is the normal place on most other vehicles to attach the ignition (brown) wire Fiat have just done something slightly different.
However, by the sound of it, you may have tried starting the car with the ignition wire hanging loose and touching earth which means a main fuse may have popped hence the lack of any power.