As you are a TV tech I will only remind you of freeze spray but not use or how it helps in diagnosis of what board to change next.
If you are not a TV tech this area is not considered user serviceable. Get repair estimates.
TV started giving me a solar type picture today. I purchased it around 8 years ago. I tried factory resetting with no luck. So I opened up the back panel and noticed some white glue type substance on a 14 pin connector. I believe it's called a CMN803. I know this is the problem because when I remove the connector from the motherboard and turn on the tv it shows no picture. But when I connect it again it shows clear picture for 5 seconds but then starts to fade to a solarized picture again. Anyone know if this connector could be the cause of the issue? Could replacing it work? And where can I purchase a 14 pin connector?