Ok, so it sounds like you've got your fuel problem halfway sorted- keep working on the overflowing carbs.
But you also have an electrical problem.
It could be a lot of things, but check the obvious things first. I can't remember if you have a voltmeter....if not get a cheap one and start troubleshooting.
-Is your battery dead? Get a charger anyway.
-Check the fuse box- these are notorious for melting, make sure the correct fuses are there too.
-Make sure all the wires are connected in the headlight spaghetti, under the tank and by the electrical components under the left side cover.
-Check the grounds on the bike.
If you have a non-original ignition switch, i.e. EMGO, it could be that too.
So many options for what's wrong....but just take your time to sort it out. Walk away for a while if you get frustrated.