I've literally never had a TV break or stop working. Ever. Especially with the new mass produced panels, what sort of Diagnostics or remote analysis could they POSSIBLY be doing?
Another tv had some bad joints on the panel, but remote diagnostics weren't going to help with big giant vertical lines.
This was a little under ten years ago.
Just reinserted them all back in and voila.
The LEDs or drivers sometimes die, but replacements are usually available from ebay or aliexpress.
Funny how one of the repairers found that his 120V only LCD TV had a 120/240 power supply board nonetheless.