My Amana Convection oven stopped working. I don't know why. It's just an oven without a stove. The screen still shows the time; all of the clock and timer buttons work, but the actual cooking ones don't (bake,broil, convection bake, clean, etc). When i push them, nothing happens at all as if i didn't touch anything. What could be the problem? What can i check for? Thanks.