You downloaded a version with extra options (Lua, Haptic, GPS) for a radio with limited memory. Fix: Use Companion 2.1.9 to compile a stripped-down version: uncheck "lua", "spectrum", or "pseudo_rtc" in the build options before downloading.
: Improved support for various protocols, including better DSM handling and rotary encoder fixes. opentx 2.1.9 download
Boot the transmitter into by pinching the two horizontal trim switches toward the power button while turning the radio on. You downloaded a version with extra options (Lua,