Power.....
From what I see of your electrical drawing, you only have two fuses that should be live, the rest are spare. The bottom two fuses are the battery, 15 amp and the MPEM, 5 amp.
Do a continuity test on the BK/PU wire from your DESS switch to your BK/PU wire at your cut-off relay switch, which is right beside your solenoid.
Connect your lanyard to your post, check to see if you have power from the YL/RD wire at the solenoid when you press the start/stop button.
With the lanyard still in place, take a reading on the coil for continuity using the black and white wires going in. Then, using the black connector in the center lug (ground) of the coil, check the power on the BK to White and Black to Black ..........let me know what you find out.........:cheers: