Try using ssh to get in and reboot the device. Sometimes it's a bit random whether or not it starts up properly. You'll probably have to rewrite your sd card anyway, when I tried uninstalling hildon-desktop, it removed that package and nothing else. On restart (I had changed the uxlaunch line back to mcompositor) it launches into the dialler app which keeps restarting when you close it and it wasn't possible to ssh in.