Why is my 3DS going berserk?

First off, I would like to thank anyone who answers this question I also do not know if the video of the problem is linked or not so I will describe it as best as possible. So the problem I am experiencing is that whenever I turn on my console, it could either work fine for a little while then all of a sudden go wild, it just spazzes the cursor on the home menu, moves my character without physical input, or just opens menus. As far as I remember I have never gotten the DS wet. I've tried replacing the circle pad but the problem continues. This is my childhood DS and it means a lot to me.