Flashing your TEF 6686 might seem to be tricky but it isn’t.
Even more it’s almost impossible to brick your device doing a firmware update.
The official firmware release can be found on Github.
If you are a bit adventurous you might go for the Beta releases by Sjef Verhoeven.
These firmware versions can be found on this Discord channel. (channel).
I’ve often and successfully updated the firmware on my metal cased TEF6686 and on my Deepelec DP-666.
How to do this update?
Check the instructions below made by fellow FM enthusiast Guido Schotmans.