Problem with Aspire 5750G

Hi. So my laptop has had this problem for a while. Probably a couple of years ago I spilt hot chocolate on my laptop. My dad managed to open it and clean it up (he knows alot about computers) and we got it to boot and it has functionally been ok the only thing that died was the keyboard so we had to replace that. But the problem ive had for a while is that if I ever rest the palm of my left hand hard (between the keyboard and the SD Card slot) when typing, my screen starts flickering and sometimes the flickering goes if I release my palm but the computer is frozen and I have to hard reboot it. Apart from that everything works. Does any one know what this problem is related to?

Thanks