That's some other symptom so I won't say it's that. If the screen backlight has failed, you could do the usual flashlight test such as https://www.youtube.com/watch?v=xUzCLgoSPGM
That's a very complete video on LCD TV basics. You as the TV repair tech would want the service manual and know about the lethal internal voltages so with that out of the way the service manual is key for great diagnosis. That is you use the manual to check test point voltages and follow the service diagnosis trees.
I bought a LG LED 42LV3500 TV from a Best Buy back in 2011 or so. It's been a great TV overall! But the other day I turned it on and it surprisingly didn't bring up any video.
The red power button blinked twice, then it does go to its usual blue color but it is so dim you wouldn't notice it unless you were really looking.
The TV has audio but no video at all. The screen it totally dark.
I did research and know about capacitors but when I took off the back they all looked okay. I thought I'd replace them anyway, but I couldn't find any of the correct capacitors to buy. So Instead I bought a new power board. Today I installed it but nothing changed. The screen still wont come on.
Any suggestions on what might be wrong and how to fix it? Or am I better off buying a new TV?