After researching dozens of user reports and testing multiple builds, here is the final verdict:
The firmware on this board is the operating system (usually a Linux kernel specific to embedded TV systems). It contains the bootloader, the kernel, and the root file system. Crucially, it holds the . tp.sk506s.pb802 firmware
If you are in possession of this file, or looking for it, it will typically manifest as: After researching dozens of user reports and testing