No pictures but I have sound

@kellyf you are saying that "the picture goes out" which implies that at first it shows then it fades out. That could be an issue with the power board as well as the backlight. Once the picture is dark shine a flashlight at an angle against the screen to find out if you can still see some display. At this point you would have to open the back of the TV and check for damage to the power board etc. Look for any obvious damage like domed looking or leaking capacitors. Post some images of your boards etc. with your question. That will allow us to see what you see. Use this guide Ajout d'images à une question existante for that. You will need a multimeter for any further testing, so let us know what your initial inspection shows. Also, confirm that your TV is a LG 37LF65