If your Television's screen lights up but there's no picture, image, or words on the screen, its just a blank backlit screen; then most likely the cause is either a bad T-Con board or a bad LCD Panel/screen.
In this video we have a Philips LCD TV model 40PFL3705D/F7 that powers on with backlights but no image. I will show you how to troubleshoot it to isolate whether its the T-con board or the LCD panel.
Even though this Philips model is an older CCFL backlit TV, the troubleshooting method is still the same on all Televisions that use a T-Con board.
Here are a few more good videos on how to troubleshoot Televisions with Backlights but no picture on the screen.
https://www.youtube.com/watch?v=jLd6QO7Z7m4&t=398s
https://www.youtube.com/watch?v=6hLO22V4_V8&t=191s
FOR TOOLS AND TEST EQUIPMENT:
https://bigdogelectronics.us/
KAIWEETS MULTI-METER USED IN VIDEO:
https://kaiweets.com?sca_ref=1488882.UqPmA1Bjbh