The screen on my LEGO MINDSTORMS EV3 brick has just stopped working. It is blank. I have tried turning it on and off, installed fresh batteries, and I can even hear the selection sounds. Additionally, it responds regularly when I connect it to my computer. I've had my NXT for three-and-a-half years, so it's not new. Is there an easy/feasible way to fix it, or a cheap way to get it replaced?