Green horizontal lines when pressure pushed near the motherboard, freezes computer, then restarts.

My Mac (13", Mid-2012) recently gotten some water/moisture damage. I believe some had gotten inside the keyboard and into the motherboard, no major damage has been done after it has been dried off. Although when holding the Mac, pressure pushed behind the computer (probably near the MB) green horizontal lines flashes, freezes the computer (mouse not moving) then goes to a black screen and re-boots. I just want some advices on what to do before opening up the back off (or even not at all).

Any suggestions would be great!!!