The service manual. Without it and some electronic tech skills you are shotgunning. You already replaced the usual and it didn't get fixed.
It is LED so did you test the LED strips? Google "How to test HDTV LED STRIPS" if you need more. But at this step and actually before I work on a set, I demand a service manual or don't want the job.
Hello i have a LG TV model 55LF5700 and after replaced the main board and the Power supply with a new one.TV is on but image is blue.Thanks any suggestion what could be?