Entered in Service Menu by holding Menu&Menu... then after a while the TV shut itself down (because of no activity from my side). Now when I try to start the TV, OSD blinks three times and then the TV goes off. Anybody knows what might have happened?
Hope you can get it working again. Perhaps an e-mail to LG or a call to service will know the answer. If the TV is still under warranty, you don't need to say you were in the service menu, just tell them what the TV is doing now?