LG 42LS575T intermittent backlight issue

[dynomoman]

Hello,

Having an issue with an LG 42LS575T that has an intermittent backlight problem. This model has a separate LED driver board.
The set seems to run ok for a few hours. Turn off and next day it wont always come on. I get sound with no picture. Shine a torch at the screen and I see the LCD is working ok, just backlight dropped out. I tried freeze and heat treatment but it shows nothing

Has anyone seen this issue before on this set ?

Thank you!