Mitsubishi WS-65313: cannot access menu or view inputs

I just bought a MIsubishi WS-65313 off of craigslist. Initially, the TV wouldn't turn on. I finally got it to turn on, but I am having trouble getting the functions to work. i press the input buttons and it occasionally changes inputs, but it doesn't say on the top of the screen what the input name is, or if it doesn't it flickers heavily. Similarly, I cannot pull up the menu, or if I do occassionally, the menu seems to flicker into life, and can barely access functions. What steps can I take to solve this problem?