The Green screen usually means there is no signal to the TV.
There are two likely causes:
1). The TV is connected to the STB incorrectly if you are using component Cables. Make sure that audio r and audio L (red and white) are connected to the same input as the component video. Make sure the component video cables are correctly connected,
i.e. Py to Py, Pg to Pg and Pb to Pb at both ends. IIRC on component cables, synch is on the Green cable, so if you misconnect that one, you will get no picture at all.
2). Many TV's have more than one HDMI input, try switching the inputs from the remote control, and see if you can find the one you are actually connected to.