I have a Westinghouse model # LD2657DF that went dead, black screen no sound no audio. So I put a new main board in it and now the backlights come on but no audio or video. I am getting 12 volts to the inverter board but do not have a schematic to check other voltages. I do not get the menu on the screen, and I have tried different input settings and it makes no difference. Also, I am getting the standby voltage but the led for standby does not light, could that be a problem?