A primary source for this specific firmware is KenotronTV , though it often requires registration or a paid subscription to download.
Technicians frequently share these files in specialized "LCD/LED TV Software" channels like Hashmi Telecom . Installation Warning Download LDD H510 B138 3840x2160 768M Magic55 part03 rar
Open the back of the TV to confirm the board model is exactly LDD.H510.B138 . A primary source for this specific firmware is