My nikon D3100 just don't come on

basically i was taking pictures one day and after a while the camera went dark after a while it would not come on at all no matter what i did. at one point it thought it was the battery but i went home and charged it then it came on for a few seconds then the screen started flickering other colors and shut off put it down for 2 months and it still have not turned back on even after changing the battery