Finding specific firmware files like can be tricky because they are often model-specific and hosted on technician forums or manufacturer support pages rather than general websites.
Do you need help identifying the (e.g., Skyworth, Akai, Sansui) so we can find an official support mirror?
If you already have the .rar file, you usually need to extract the MstarUpgrade.bin file to the root of a FAT32-formatted USB drive to start the update.