i wonder if it works for you. In my tryouts to update from E17 to E19 i ended up "bricking" the system for couple of times. The reason was, that i tried to update inside a running E17 instance. So the workaround was either to install some LXDE or XFCE env. and from it to perform the udpate -or- to start up directly to console (without xserver running) and to compile it from sources/use apt-get/aptitude ...