If you don't want to use Companion, you can use dfu-util via command line:
Downloading and installing OpenTX 2.1.9 is a straightforward process. Here's a step-by-step guide: opentx 2.1.9 download
: Version 2.1 introduced a major change in how telemetry data is handled compared to 2.0. If you are upgrading from 2.0.x, your telemetry screens and sensors will need to be rediscovered and reconfigured manually. If you don't want to use Companion, you