Why is my LG TV showing everything in green?
Green screens are caused by loose cables or bad cables.
How to Fix
If you only have the aerial cable plugged in then try removing it and see if that makes any difference.
Also try unplugging the power cable and then plugging it back in after 10 minutes. This will complete a power reset and may help to resolve the issue.
Finally try changing all the cables for ones that you know work and make sure that they are all connected in securely.