I wouldn't say it's a lost cause, but it's definitely not something I would expect to work without issue.
As to the point of the person who you asked about the repair. It's definitely not job everybody can or should do. It requires a lot of finesse and the ability be very accurate with the hot air. The risk of damage to the display is not insignificant. because the TCON board is so close to the panel.
The schematics for the logic board are widely available if you know where to look, but I think in this case its less the schematics not being available. You don't need a schematic to remove the IC from one board and move it to another. But I respect when a tech knows when they're out of their depth. I would be hesitant too, even with microsoldering experience. Some people do stuff like that all the time, but it's not an every day repair for sure.