CDI wiring help me please!

[Cwrigs1]

My teenage son bought a demon x Detroit 170 from his friend last week, they started it up and he test rode it and all seemed well. Brought it home, kicked it up and it started first kick. Day after he kicked it up and it just would not start. Tried bumping it and it just wouldn’t get going.
There’s no spark at all.
So we looked at the wiring and it was A MESS! Tested continuity and some wires didn’t have it so We’ve bought a new wiring loom with CDI, coil pack and kill switch.
We know how to wire these back up mostly but a few bits are puzzling. The wire to the coil has 3 wires, one I know needs to be grounded but both have the same fitting on the end and fit on the wire from the coil so how do I know which one is to be grounded??
Secondly the kill switch wires, coming from the kill switch to the clip is 2 wires, green and black/white. Same from the clip to CDI, BUT when the clips are put together these wires are opposite each other - so green touches black/white and vice versa. Surely they should be green to green, black/white to black/white?
If this does not give a spark what else could it be? Son thinks stator?
I know nothing about bikes, Google has helped and sons grandad helped explaining the electrics (he’s a gas engineer so knows a bit but not enough to help). Please help. My son is autistic and has saved up for so long for this bike and his friend has disappeared off the face of the earth and he’s devastated to say the least!