Hi
I tried the An-Klamm's method
I heat the yellow marked area and then I test it.
If that works, then you can let it cool down completely and try only one IC etc. Then you can narrow it down.
NOW, The backlights turn on, and i have 12V on the Tcon too, the led on power supply board didn't flash.

but NO IMAGE....
an idea?...

Hello.
I'm exactly the same problem wih my LG 65UB950V.
[FONT=Calibri][FONT=Arial][COLOR=#111111]I have the 3,5v standyby, when i power on the tv i have also the 12v and 24v! [/COLOR][/FONT][/FONT]
[FONT=Calibri][FONT=Arial][COLOR=#111111]the 12v for tcon supply is missing[/COLOR][/FONT][/FONT]
[FONT=Calibri][FONT=Arial][COLOR=#111111]NO backlight [/COLOR][/FONT](backlights turn on when i put 3.5V on DR-ON et P-DIMM 1 &2 but no image)[/FONT]
[FONT=Calibri][FONT=Arial][COLOR=#111111]A led on power supply board flash 5 times[/COLOR][/FONT][/FONT]
[FONT=Calibri][FONT=Arial][COLOR=#111111]Etc…[/COLOR][/FONT][/FONT]...