sounds like stator and/or voltage regulator has had it. hard to say which one. i would first check that there is sufficient voltage over all 3 phases coming into the regulator and then the regulator post exit voltage.
You need to connect the two wires coming from the loom to the sensor. If you actually 'cut' the cable it should be easy. Make sure you connect the wires coming from the loom, not the sensor.
It does sound like a kickstand sensor issue, as the sensor only works when the bike is in gear. To check, you can bypass the sensor by disconnecting it's cable and then joining the two wires together so there's a permanent electrical connection. If that solves the problem, you need a new kickstand sensor.