I went through the steps listed at
Open up a terminal
Switch to root user using su
Mount the partition in which you have Antergos installed, on the /mnt folder. You can do it by using: mount /dev/sdXn /mnt with the X being the letter of your drive, and the n being the number of the partition.
Change the root using arch-chroot /mnt. This open some kind of root session on that drive, allowing you to make changes to the system without booting from it.
Uninstall lightdm, and install gdm:
pacman -Rcns lightdm
pacman -S gdm
systemctl -f enable gdm
But still I see just the blank screen when it passes the antergos boot screen. Can you please help?