Thank you Herlufhansen!
Kind of you, but I ended up contacting B&O support again.
This time a kind man did help me out – he sent me the pdf guide and the firmware file. And it did fix my M5!
He even offered me to send them my M5 and they would do the FW upgrade for me for free, if I had any troubles upgrading my self!
The local B&O dealer wanted 700kr to do the same upgrade for me…yuck!