Try running the XVESA drivers.
Boot into a rescue shell and type
sudo dpkg-reconfigure xserver-xorg
Choose "Vesa" or "Xvesa" as your driver. Vesa is the failsafe video drivers and works on basically every system.
Edit: It seems this method won't work with the new version of X.
I believe you can edit the boot options and add xforcevesa to the end it will work though.