How can I get my SM-G906K out of a bootloop?

A

AC Question

SM-G906K Bootloop

At first i want to apologize for my bad English.
I got an big problem with my S5, it wont boot anymore. I tried to access the recovery mode, but also there it ends in a bootloop. This phone pertains to an friend of mine, wich told me that he didn’t do a thing on that S5… however, the KNOX-bit is set.
So, I don’t know what I can do now. I tried to flash it via odin to the newest lollipop and a new recovery mode… both variants hasn’t worked for me.
Got anyone a idea what I can do to rescue that one?
Thank you.