You need to get to the heart of the problem. Try opening up the laptop and blowing out any dust.
I've tried opening it before with no success. I don't know much about computers in general and it's pretty worrying if I end up messing it up.
It's a weird model, to open the whole thing you have to take the keyboard off as well which was what I got stuck at before. However I can try and get some dust out since I haven't done that in a while but I don't think it will help much.