I have a Panasonic Cordless phone system. Model #KX-TG7731. All of a sudden the message counter light, the message indicator and the on/off indicator lights do not light up. I have un plugged and re plugged the unit into the electrical outlet. When I re plug the number 88 appears in the message counter and the other red lights go on for a second then all the red light go off. Can you help.