Serious head ache with electrical issues

Alright I went riding a couple months ago and my head gasket blew, I parked my quad and ordered the gasket. Long story short I was too lazy to fix it, I finally tore into it and fixed it. Now I’m ready to test it out and have a little fun right? I put the key in it and turn it on, no lights, neutral light or even the start button working! I searched and searched and it’s probably something simple, but I am lost! I charged the battery and tightened the negative up on it because it was a little loose. The quad set out in the weather for probably 3 months, stupid me. Everything worked before I left it outside.
This is on a 2000 400ex by the way, and if anybody knows why I have to wiggle my kill switch off and on real fast for it to start that’d be great, lol. Done it since I got it, I replaced the whole switch on the handle bars and it still does it. I can short across the solenoid and get it to start the key and kill switch work, but the lights and neutral light won’t along with the start button.