Hi @fabianio!
One of the things that might be useful to look at is this documentation on how to modify the config.txt remotely through the dashboard: https://docs.resin.io/reference/resinOS/advanced/#config-txt – that’ll make it much easier to reproduce things going forward.
To select the mini jack for audio output, you can run amixer cset numid=3 1 on the command line, adding it to config.txt doesn’t really do anything.
You can test this out by connecting to the device terminal by going to the dashboard, clicking on the device in the list, and on the right hand side connect to your application terminal and running the command there.
Let me know if that works!