@seno360 ,
What is the model number of the TV?
Sounds like the backlights aren't working.
Initially try to find the service manual for the TV online. Search for "LG (insert full model number) service manual".
If you find it it will show the backlight power circuit diagrams which will help so that you can test the circuit to locate the problem.
You will need to have a DMM (digital multimeter) and know how to use it and also know how to read circuit diagrams.