Similarly for Lenovo T420 nvidia NVS 4200M except I can switch to text mode with cntr+alt+Fx, switch back to intell and restart lightdm. I can also confirm that switching between nvidia and intell had worked previously for ubuntu 14.04 however I cannot tell exactly when it stopped.
Similarly for Lenovo T420 nvidia NVS 4200M except I can switch to text mode with cntr+alt+Fx, switch back to intell and restart lightdm. I can also confirm that switching between nvidia and intell had worked previously for ubuntu 14.04 however I cannot tell exactly when it stopped.