Hello,
The ADV7842 evaluation kit is not designed to be used in a "loop-back" mode.
The presumption is that you have a HDMI source - (generator or DVD player) into which you plug the ADV7842 HDMI inputs and that you have a HDMI sink (TV or monitor) where you plug in the ADV7511 output.
All the scripts that set up the ADV7842 DUT have this set-up presumption.
regds,
Denis