Ok, i don't know how to help you anymore except the least thing.. Maybe when you write this commands you do some mistakes, you need write this commands correctly, spaces, slashes etc.. When you press enter, you will not to see anything and only after the last command (devel-su user -c "killall -KILL messaging-ui") you will see output.. In this command (rm -f /home/user/.mms/profile.conf), you output should be: or nothing or something like: no such file or directory.. If this not work for you, search in this forum about flashing PR on Mac PC..