Welcome.
That is completley normal for a corn snake that age. At that age the snake thinks everything is out to get it. Since you bearly got it, leave it alone for a week or so, then you can start handling it for short periods of time to let it get use to you. It is also normal for the snake to be hidden all day. They come out at night, and do all their exploring there. So dont be scared if you dont see the snake drink water, or switch from the warm to the cool side.
What are the tepuratures of the warm and the cool side?