I see this posted a lot, "My main fuse keeps blowing".
Well, I had the same issue. As soon as I turned the ignition switch, the main fuse would pop.
Now to find the cause.
Rather than tearing the entire bike apart, disconnect the main parts first.
The right control wires, then left, sub harness assembly, etc..etc..
After you disconnect one assembly, put in a fresh fuse, (or use your multimeter) turn the ignition. If it still pops, it's not that component. Reattach the connections
Once you disconnect a major component and the fuse stays intact, you have you culprit.
I'm certain there are more technical ways to do this, but this really worked out well for me.