My DCT700 cable box, SN M91131FXBA28 has stopped functioning. I cannot power it on. The green light does not come on. I checked the power supply and it is delivering about 15 volts DC. I am using what I believe is called a Champ remote, model 2020B0-B1. It has fresh batteries. I have disconnected the cable box power for a minute or so, but still not operating. What next?