Moin,
the
service page has a spare parts graphic for that saw. Unfortunately, there is no wiring diagram ... it looks like the loose wire is one of the two connecting the suppresion capacitor and the motor, but it is hard to guess from the photos where the leftover end of the broken wire might be. Maybe you know someone with a background in electrics? The Bosch Service Center surely can help, too, but I do get the slight feeling, that the saw might be just a tiny bit out of its warranty period, so this option would probably cost a few Euros.
Hope that helps anyways!
Cheers,
kuraasu