I recently purchased a YUMA 2 this spring. We have been using it for about 3 weeks and now the unit doesn't seem to power up. I will depress the power button and the green power light comes on n the top left corner for approx. 2 sec then goes out and nothing happens. When I plug it into the wall charger, the battery light doesn't come on to show that it is charging. And if I attempt to press the power light while plugged into the wall, no lights come on at all. Any Idea on what could be wrong?