KISS... Keep It Stupid Simple
Start with making sure the side stand switch, neutral switch, and cutch switch are working right. The side stand switch is an easy bypass, unplug the switch and run a jumper wire between the two contacts on the wiring harness side. The neutral switch is also an easy bypass, there is a green (maybe it is blue I forget which) wire coming out from the back of the transmission on the underneath side, unplug it and and hold it to ground while the key is on, then try and start the bike...
If the bike still won't start, take apart the starter button and clean the contacts, and make sure the spring isn't to loose.
Check for continuity between the start switch wire output and the solenoid contacts. If no continuity, you have a problem inside the fuse box or a broken wire.
If every thing tests out fine thus far, try jumping with a car battery. If It jumps, you have a week battery. If It doesn't jump, you have a bad solenoid.