If I take your word and explanation as-is this sounds like a mainboard to LED driver failure or worse a panel failure. Have this one diagnosed by a LG technician. Yes, they might have some firmware update to fix but that's a long shot.
In other words, get estimates.
My three year old 42LB700V TV has been showing bright circles all across the screen in a perfect checkerboard pattern.
The circles are more visible on bright backgrounds with plain colors, but they seem to be present at all times (even when 3D is on), though they are less easy to spot. They are of the same hue as the picture on screen, but brighter.
They are easy to notice, though they do not really 'distort' the image quality.
They are difficult to capture on camera (I have tried and couldn't), but I will post pictures if necessary.
I had first noticed three of these in the lower left corner of the screen a few months ago, but thought it was just reflection. Well, apparently they are more than just reflections.
I have tried altering the picture settings, tweaking brightness and contrast and backlights to no avail. In fact, I turned the backlights all the way down, and while the screen became darker, the spots themselves remained.
What's causing this? Is it a hardware or a software issue? What should I do? How much does repair cost?
Thanks in advance