Tv screen goes black after LG logo

jeffrey latreille first you need to rule out your inputs as error source. Remove all of them (especially if you have some sort of cable box, sat box etc.). Unplug your TV and unplug all input sources. Hold down the power button for 30-60 sec. Then reconnect one input source (preferably local, something like Game console, DVD/BR player). and make sure you use a known-well HDMI cable, if that's how you connect. Lastly reconnect the TV and try to turn it on. See if that changes anything.

The no video issue can be related to a bad backlight inverter circuitry. A simple check for that would be to darken the room and turn the TV on. Then use a flashlight and angle the light at the screen on different areas. you might make out some shadows or see a slight grey color. Your model uses an backlight circuit on the power supply board.

If you do not see anything it's time to remove the back cover from your TV. Check all the boards for damaged components and reseat all the ribbon cables. Measure the voltage on your T-Con board. Next to the connector is a Fuse marked as F1. You should have 12V on that. Next check the connector that has the cable from the main board in it. Make sure that you have all the voltages on that connector and pay particular attention to the BL_On

Let us know what you find out. It is possible that this is a backlight array issue but let's rule out other causes as well. Just in case.