Using the schematic as your guide physically look, and feel along the length of, at every single wire in the circuit. Start with the main power wire and ground to the starter. Followed by the solenoid circuit.
After doing all that "in detail" and it's all 100% good, look at the starter circuit schematic for the line that goes down from the starter relay to the starter solenoid. Remove relay, insert a wire into the correct connector that goes to the solenoid, and touch the other end of the wire onto the battery terminal. Basically, jump it.
If the car cranks right = Problem is in the solenoid circuit
If car doesn't crank right = Problem is in the main power feed circuit