That's a toughy!
What happens when you take your thumb off the starter button? (I assume the starter doesn't crank, it just instantly kills everything)
Everything come back to life? If so it's a huge drain somewhere, so could be one of a couple of things.
First, how is the charge on the battery? If it's weak, that's what it will do.
2nd, if battery ok, it's a short somewhere, and probably on the side before the fuse, possibly on the heavy wire from the battery to the starter solenoid. This usually isn't fused.
3rd, check that the wire from the starter button isn't pinched on the handlebar, pssibly from the switch being rotated in the accident.
4 Can you kick start the bike ok? If not, maybe the motor is seized/stuck/ etc nastiness.
See how you go with that, if no luck repost.
Good luck, you'll need it, electricals are the worst. And I used to do a lot of it.
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