Is there a specific pattern, or just steady green? It means something has malfunctioned in the set. First thing to try is unplug it for a few hours, and plug it back in. if that doesn't work, i'd contact a local repair shop for a diagnostic. if you are feeling handy, i'd get a reapair manual, and voltage meter.
Unplug your TV, press and hold volume down & channel down on the TV SET. Keep holding them while plugging the set back in, and power on. You should see the letter K on screen, if not, the backlight, or power supply is probably bad. If it stays on, use your remote and arrow right then look for "fact init" and set it to on. Then arrow back up to "fact init" and hit enter. Let the set go back to green and unplug, and replug the set in after a few seconds. The set should now be at facroty state.