Install xorg and complete mess

Installed xorg

Last time I tried install xorg on my arch linux, it was failed because I didn't reach the mirror server (which is in Taiwan I choosed because I couldn't find mirror in japan). So this time I selected several servers in /etc/pacman.d/mirrorlist (Taiwan, Singapore and California).
And force pacman to refresh the package lists.
$ pacman -Syy
After this, tried to install xorg.
$ pacman -S xorg
And it worked! I successfully installed xorg. I tried start mate by executing startx but system said no such command. So I think I should reboot and then I rebooted and ...

and complete mess

After reboot it seems to be fine before the screen blinking oddly. Now it completely failed. I can't back to shell and can't run any command. Screen is blinking endlessly. Sigh