No startup logo or picture on led tv 42ln5300

No startup logo or picture on led tv 42ln5300

Standby light is on and backlight leds are on, but no logo or picture on screen. I replaced power board. All voltages on connector to main board are ok. Also replaced main board and t-con board. Still no picture or startup logo! Any suggestions?

ANSWERS:

"If you replaced each of the boards with new ones, then either the panel itself is bad or you received a bad board. This TV has only 3 boards and you have replaced all 3. Do you get sound?

Dan"