Hi again!
So I tried to do a firmware update with offline mode, it failed.
=> booting, all led on, cannot do anything
Tried in update mod (Shift + Octave) and updating from Minifreak V (no firmware was detected), failed.
=> Assign was blinking and nothing else, no reboot
I closed the app, powered off/on and it boots again, with presets and all!
AND NOW the magic! I can plug my headphone and it works fine!
I was afraid to have bricked my minifreak for the weekend but it seems to work fine right now!