Can't help with a wiring diagram. Lots of bikes built in the last couple of decades are fitted with an immobiliser and they are far from trouble-free. The first step when the engine doesn't start is to check the immobiliser is disarmed - if the bike is equipped with one. Often that information is found only in the owner's handbook or at the dealer.

Although wiring harnesses aren't very long on bikes there is usually quite a lot of it and manufacturers don't make it any better than it absolutely has to be and there are places where wiring can be stretched or chafed and where it jumps from the frame to the steering there is lots of flexing.
I suggest you expose as much of the wiring as you can and inspect it carefully for signs of damage. Check whether the fuse(s) are ok and have power on them will give you a start.