At the shop we use this old advice about which board to replace next. HOWEVER a failure like that can damage the LCD too so our advice is to write it off as even if we fix it, we have to void any warranty on the repair. Kind of like they do to heavily damaged cars.
Oh, that advice? "Replace the cheapest parts first."
42" LG flat screen tv, 42lc7d. Wouldn't power up. Internal power supply board had 6 capacitors blown. Replaced whole board. Now it turns on. But if it has a video signal screen flashes, audio stays constant and it turns off. But if no video signal is present it will play audio and screen wI'll stay on. I can go trough all menu and settings. It displays all of it but once you give it a video signal it's flashes and shuts off again and I can hear a noise coming from the back of TV when ever it flashes. Any thoughts?