Got a LG 55LM4600 for $50. The unit powers up with the LG logo (no flickering or issues). After the logo appears, the screen goes to almost black; however, you can make out images but they are very faint. The audio works fine.
I’ve noticed that once the backlights are on during the LG logo start, but not after this. Is the problem the LEDs or the LED driver? Or something else?
I checked voltage from Power Supply to Main Board and it all checked out.
I suggest you measure the power supply voltage going to the LED driver board as it turns on. If the power supply sags then that could be the problem.
If the LEDs come on then the problem could be something more complex so don't invest too much. Might require a new main board.