The reference refers to the main PCB (Printed Circuit Board) used in the Hisense H50M3300
If you obtain a firmware file (often named something like upgrade_loader.pkg or Hisense_H50M3300.pkg ): Download File RSAG7.820.6392_Hisense H50M3300.p...
: Place the .pkg file directly in the root directory of the USB drive (not inside any folders). The reference refers to the main PCB (Printed