Here is SW for your tv (V320 if you have older):

https://mega.nz/file/NgoUlRQZ#Gts0X2...hMgjqHotTvKeTg

Try updating it and after that do a factory reset to rule out SW issue

Does the LCD turn off or does the backlight turn off?!

@EazyBone it's and FALD tv with LD board, same principle as that 85x90CK you did the other day. If it was backlight error, it should trigger 4x red blink...

LCD is meant to be dissasembled with bezel so it's a right thing to do. Good luck!...

How much working hours does it have?

It's a FALD tv so normal rule "if one LED failed, probably other ones will fail soon too" isn't correct. Since it dims, turns on and off different segments regarding to picture on tv, other leds are probably fine. This segment could have died just because one LED was fault. Or because it was at 100% backlight all the time and at that part of the screen there was something that needed to be bright. Or maybe it was demo set and was working 12 hours a day on vivid mode again with 100% backlight.

Sony uses high quality parts,...

It's not a component it's just a cushion

Looks to me like it's some garbage under screen

Here is SW for your TV:

https://mega.nz/file/wtYWHYCT#6iktYW...Jq_Pjg6hjSpxnw

(V8-T658T01-LF1R820_Test_Version.zip)

Download SW and unzip it. Put Upgrade.pkg directly on root of usb stick. Stick must be FAT32 formatted.

Unplug tv, insert stick, press power button ON TV and keep it holding while plugging in tv in socket. Upgrade procedure should start.