Samsung s300 screen freeze problem

I've got the old Samsung s300, I've had it for about 4 years and my father has had it for a year or so before that,

Problem: however whenever I close the flip phone and then open it, and it only showed a blue screen, it responded to nothing apart from turning it off

Solutions Tried: Taking out the battery and putting it back in, however no change.

After this, I've had it open and closed and re opend and the same thing happend

Another Problem before the first problem: Also before this happend, twice it went all weird and the screen went mirror image, I do not know how this happend but I just took out the battery and put it back in.

A friend of mine recommended resetting it by the reset code, however I do not know why it's acting like this and whats the best way to solve it.