I am Not a Computer Repair Specialist, yet anyways lol but with the help of this site, google, & youtube, I'm sure that i will be soon enough, But aside from that I am a Certified Electrician and just reading your the Synopsis of your problem, I am almost 100% positive that your Diagnosis is a Electrical Short, Find the Short and Replace that component, wire, or connector and your problem is Solved, Good luck, Hope you figure it out, and when you do I would greatly appreciate if you would be able to inform me on what is that you find out, Problem & Solution, Thanks