Recover soft-bricked wrongly mounted Galaxy S4 gti9506?
Ok fixed the problem by installing firmware from sammobile.com. The Odin flash failed at the hidden.img, but I could recover the thing by running the instructions here:
http://www.s4miniarchive.com/2014/07/solution-what-to-do-when-odin-fails-at-hidden.img.ext4.html

And I have my wifi back but lost root (but that's not a big deal).