26 Apr 2017, 12:16

@Usato The aim is to mount /dev/mmcblk0p1 (the very first partition of the sdcard that is in fact noobs) and add a config.txt from here

just out of my mind, try :

mkdir -p /tmp/noobs
mount /dev/mmcblk0p1 /tmp/noobs

If mount succeeded, you should be able to cd /tmp/noobs and create a config.txt from there. Do you know which lines you're supposed to add to the config.txt for noobs ?