I been troubleshooting this for a while.
Thought at first it was a low battery bc a jump start it worked, worked a couple of times but the then with the battery fully charged it wouldn't start and neither would the jump. It's left on 1.5A tender so it should be good right? Battery passed load test, and wasn't as simple as I expected to extract, I took it in thinking I needed to replace it. When I jumped it you could hear the relay pull in so I was thinking it didn't quite have enough juice to pull the relay in, maybe a bad cell in the battery or some reason there wasn't enough current going through despite it showing charged
So now it wouldn't start with the jump, no relay kickin in ....? wt* .. I am now thinking maybe the gear sensor or something along that lines, you know how it won't start unless you pull the break if it's in gear.... I fiddled with the shifter and noticed it wasn't always indicating in the dash the gear, most often in P, then it started ... but it wouldn't start with the break on in H or L or even N ...  coincidence? Only had this result once.  I can't seem to get a consistent pattern to get a definitive answer here.

Just to clarify, all the other electronics seem to work when the key is on, but it will not crank?  or is it cranking but won't start?  Does the kill switch seem to work?  If it is activated it should make the efi light on the display come on. At least on my older model it does.  So if the kill switch is shorting it may show that.  Also, make sure your break switch is working. Do the brake lights come on? Can you hear the relay click when you pull the brake?
Also, check your main fuse. If power is not even getting to the solenoid now it would probably be a blown main fuse. Mine is under the seat next to the solenoid/start relay.

Lights, dash all seem good. Relay, it doesn't click in, we'll it does, randomly, and when it clicks she cranks, my persistence seems to get it started.  I was lookin for a sensor or something, Brake Switch, think you may be on to something here. Where is it? Can I bypass it to test? Would it prevent the bike from starting in P?

[2015 Z Force 800 53/Trail EPS]

My gut says it's a switch problem. May be the key,kill or one of the interlocks..or even a AUX relay.

ok, still having this issue. I have eliminated the battery as a problem. I am now thinking maybe an issue with the fuel pressure, pressure sensor .... ??  if I flip the kill switch it primes, then if I rock the switch it it will prime again, and sometimes it will keep priming and other times it won't. At random it seems it will try and turn over.  ...?