If you have bought your Transmitter some time ago, and you never did an upgrade to OpenTX, chances are that your bootloader didn't come with the firmware management screen. So if nothing happens when you switch on the transmitter while pushing the trim buttons for rudder and ailerons towards each other, you need to use this upgrade procedure:
After downloading the firmware installation software, run the setup file "DfuSe_Demo_V3.0.3_Setup.exe".
After installation, you will have an entry in your start menu (in some windows versions it is on newly installed apps), where you can start the "DfuSe demonstration" application.
After you started this program, connect your transmitter while it is off with a mini usb connector. Now it wil detect your tranmitter, and you can start the upload from the existing firmware from the transmitter to your PC. This step is important, in order to have a backup to be able to return to the original state.
Click "Choose..." in the "Upload Action" section, and it will ask you for a file name and location for your backup. Just give it your name, like I did for "Neil", "Mike", etc.
After selecting "Save", you are ready to upload. Click on the "Upload" button, which isn't greyed-out anymore, and the upload wil start.
It will pop up with a warning message, click OK, and a copy of the firmware on your transmitter will be transferred to your PC.
Now you are ready to download the new OpenTX firmware to your Transmitter. Go to the Download section of the app, and select a file for the download. There are several files that came with any JustFly package, all with the extension .dfu. Make sure you select a plus version if you have the Taranis PLUS.
Now check the verify button, and click on "Upgrade".
A warning will pop up, and after selecting OK, the new firmware will be downloaded to your device.
After a short time, 30 seconds or so, it will finish the upgrade.
That's it. Your transmitter is upgraded to OpenTX 2.0, and all your models are still there. from now on you can use the simple firmware upgrade procedures, as posted on this site.
If you want to upgrade it to 2.1, you first need to make a backup of your EEPROM.
Bonus: from now on you can access your SDCard from your computer using the mini-USB connector. Make sure your transmitter is ON when you plug the USB cable in. After a few seconds your PC will recognise your SDCards as a normal external storage device.
Ready to install al other nice stuff from this site.
Have fun and