Remove the spark plug and try to rotate the engine by hand.
If fuel / oil / water comes out then try cranking the engine to remove it turn off the fuel and move the spark plug well out of the way but try to maintian an earth so it can spark.
Assuming nothing i the cylinder stopping it from turning run some heavy jumpers from the battery directly to the starter motor + and a good earth near the starter motor - ( oil drain plug is good).
If the starter does not turn either the battery or starter is kaput.
If it turns then move the + wire to the starter connection on the solenoid.
If the motor turns then wire is good if it dosent then the wire is kaput
Now remove the earth jumper. No go = bad earth get out the wire brush
Move the + jumper to the battery side of the solenoid then run a light jumper from it to the + trigger wire.
No spin then put a - jumper to the solenoid = terminal or body if it does not have a - terminal.
No go solenoid is tost, only starts with - jumper to body then bad earth, wire brush again, only starts with jumper to - solenoid terminal = safety switch problem.
Remove negative jumpers and try starting with key after replacing the fuse. no go = duff ignition switch or safety switch problem.
This can all be done without a wiring diagram in a few minutes providing you have a fully charged battery.
From here on you will need a circuit diagram
