I purchased an android 7 inch Proscan tablet from Big Lots less then one year ago. In the beginning the tablet worked fine but now the only screen image that I get is the battery but it soon disappears from the screen. Sometimes I'll get a desktop image but that soon goes away too. Before it did it showed that the unit was only 9 percent charged and I've had it on charge for fifteen hours. I've electronically tested the house plug and the unit's power cord and both show a completed circuit. Any idea what may be the problem?