Were Is The Vigina What Is On Top Of The Battery In My 2004 VolksWagen Golf?

What is on top of the Battery in my 2004 VolksWagen Golf? - were is the vigina

Today I was home from work, about a mile from the house of my car went into a kind of standard. I went back and lock the car and then tried to restart it, and would not start. I jumped on the hood and the smell of ozone from the melting plastic, I removed the lid of the battery box and inside there is a distribution box. Who is melted, and I'm sure that's the problem. The question is: What is to replace the "officially appointed" and how much it would cost too?