Assuming you've tried all of the things discussed in the previous pagers of the thread... I offer my assistance at this point where you seem to be stuck, and nobody is chiming in. So here goes... Please don't shoot the messenger,
First off, I do not have your timeline of what you did when, so I must disregard all of that and make an assumption upon my analysis of what you wrote. I believe that you stated that you originally got the motorcycle to start by putting 2 batteries in parallel. Then while trying to remedy the original problem, you took many things apart, and now, after putting them back together again, you have a true blue no start situation, all the time, no matter what.
It's just "Hit starter switch, click, nothing," No matter what. Same thing every time. If I got this correct then we can proceed.
I've never worked on your specific model (V7's) but I'll offer a possible suggested course of action applicable to any motorcycle, to narrow the possibilities.
We start on big (systems) and move to smaller (components) as we eliminate possible causes.
The two immediate questions in my mind are:
Can you start the motorcycle by directly clipping cables to the starter and then touching the + to your other 12V battery to crank the starter, thereby effectively removing the electrical system from the equation and providing direct power to the starter itself?
No - There is either a problem with the starter itself, the starter solenoid that you took apart or how you reconnected either of them to the motorcycle via the wiring. I know it is new, but there are bad new parts. It happens. You also could have made a mistake in the connections. Only you can see that and double check it.
Yes - Then there is something happening between the battery, and the positive cable at the starter.
What is the voltage difference between what you measure at the battery, versus what you measure at the starter + connection?
You probably don't have one, but I have a digital voltmeter that captures and remembers the highest voltage reading across a circuit. They are not terribly expensive..
I would measure the voltage across the battery terminals very briefly.
Then I would measure the voltage you are receiving at the starter connection when you hit the starter button and use the electrical system.
Those 2 readings, and the difference between them, will give us a new direction to pursue.