I've just seen this. It happened on a Dell Precision 5510 for no apparent reason. My fix eventually was to change back to lightdm as login DM. IMHO, there are some very weird undiagnosed problems in gdm. I read about 100 posts on the black–screen-of-gdm problem, a lot of us grasping at straws. Many voodoo suggestions.
For me, was not necessary mess with rescue or grub or what you mention. Could do Alt-Ctl-F2 and log in on VT2. From there, run
to get X11 session. That's how we always started in old days. Can run synaptic from a terminal and reinstall lightdm. Even if you have lightdm, reinstall good because it provokes a reconfiguration, where you can choose display for login. I needed GUI session because network would not start without it. I mean, I don't know how start network from terminal anymore. /sbin/ifup does no good anymore. New network stuff too fussy for my CLI skills.
I did that, but just checked and from VT2 you can cause same reconfiguration if you do already have lightdm. Run
That opens a chooser for the login display, even in flat terminal.
If you cannot get into VT2, you could try single user mode to fix this. That must be less trouble than what you are trying. At boot,choose Advanced , select kernel and hit 'e'. Find linux line and change end to 'ro single' , cutting out splash quiet and whatnot .
This problem happened to me on a system where nothing new was installed and, so far as I know, nothing changed. Very baffling. I could see XFCE4 GUI splash from system starting. In VT2, running
/sbin/shutdown -r now
Would instantly cause the XFCE GUI splash to appear again. Hence I knew for sure the device still worked, but gdm could not talk to it.
Many people claim the Nvidia proprietary driver causes this, but I do not have that installed . I do have Intel/Nvidia graphics, however. It is apparently a known thing that Wayland display will not work with gdm in Ubuntu 17.10.
For some users, the black screen problem is more general related to video mode setting. If you have that problem, you will not see splash screen before gdm tries to start. For me, was simpler problem in dgm3. Mysterious.