Match the build number of the firmware link to the one currently on your device whenever possible.
This site has the most extensive collection of TX9 Pro firmware, though you may need a browser translator to navigate it. How to Install the Firmware tx9 pro android tv box firmware link
Often hosts direct links to updated SD card and USB burning tool images. Community Forums: Match the build number of the firmware link
The go-to forum for TV box enthusiasts. If you are looking for a Custom ROM (like a de-bloated version or an Android TV OS port), this is where developers post their "cook" links. tx9 pro android tv box firmware link