Today I flashed the ELRS 915Mhz HappyModel dual RX, the firmware with the external module and the receiver is the same and they are bind to each other, but Mission Planner says NO RC and accordingly there is no response to the sticks.
Perhaps the problem is a defective chip, but I think I missed some detail during the setup, since the pilot on which this ELRS was installed is a Matek F405WTE with a 2.4Ghz internal module.