A couple things...
The first time I ever dove into the headlight I noticed that one of the big connectors is white, the other black, but they BOTH mate to a black male plug, so I wrapped the one that goes with the white connector in masking tape. It's still there. A supreme moment of clarity for sure that must have saved me a ton of hadaches!!
Also, if you want to know what color the starter button wires are, just remove the switch cover on the right side control and look
As for reading the wire diagram, I know it's a PAIN but just find the two connectors on the diagram, and pick a couple sets of wires on one of them and see if the opposing pairs match up in your light bucket to see if you may have reversed the connectors.
After that, check all your connections. Last time I did mine, no start. Nothing. I found that the starter button wire had broken off the back of the started button. Re-soldered it back on, trouble free ever since. I suppose it may have come loose and made contact with the bar grounding it?
