Thank you codamedia, HonestOpinion and datacommando for your clever ideas. I was really optimistic with all of them but, unfortunately, none seemed to be a solution.
The lack of output still exists, it's like the pedal is completely dead or something. Fortunately, I will survive the concert without the pedal, but it's still bitter to not be able to use it.
My plan is to contact the Swedish service center asap now on monday. I will update you after that. Who knows, this could come to help someone else in the future.
Haha no worries, the volume knob is for sure turned up.
Is the firmware rollback for HX Edit also needed? I did not do that since it operated successfully with both versions.
Thank you all for your helpful answers, really appreciated it. It highlights the good spirits of the Line 6 community.