You've had some really excellent explanations of the procedure.
I just wish to draw your attention to the settings.
The Flarmtool software lets you set the Flarm's parameters and communication settings.
I usually find that my preferred settings are overwritten by default every time I update the firmware.

My preferences a
.. max permissible H range
.. max permissible V range
.. competition mode (less alarms)
.. 19200 com speed.
.. Position+traffic info active on external port (GPS+Flarm sentences) (if not, you won't be able to connect to external instruments and viewers)

Definitely worth checking. After the update has been completed, disconnect and then reconnect your Flarm, use Flarmtool, explore and adjust the settings. This will save you the time to troubleshoot all your connections and then redoing the Flarmtool procedure.

Aldo Cernezzi
www.voloavela.it