Manjaro GNOME: after services start, screen is stuck with a blinking underscore
Manjaro XFCE: failed to start lightdm services. tried manually starting it, got to the installer, installed and rebooted, but lightdm still fails to open and wont start
Manjaro KDE Plasma: sddm failed to start, cant find any fixes
Manjaro Cinnamon: lightdm fails to start, cant start it manually
How can I properly install any of these?
Are you using recent isos?
That is probably because it doesn’t work very well - if at all.
Only a handful has ever asked about it - and I really don’t think they got it working.
You could try following this guide:
It seems to be written for an Ubuntu install but that should not matter as it’s all Linux 
You also might try checking other pages of this search result i guess.
What I did to get XFCE installed on HyperV, using manjaro-xfce-21.0.3-210428-linux510.iso was to switch to console 2 (CNTRL+ALT+F2) and do the following:
Press CTRL+ALT+F2 to switch to TTY2, login with manjaro/manjaro, once you have a prompt run following:
sudo pacman -Sy
sudo pacman -S xf86-video-fbdev
sudo systemctl start lightdm
Root issue is xf86-video-fbdev s missing, so lightdm fails to start. Don’t know about KDE/Gnome/Cinnamon variants, but this worked for XFCE for me
At install time, login as manjaro/manjaro, 2nd time in multi-user mode, login as an admin account (you)
Can confirm this also works when creating and connecting to a VM from Windows Admin Center.
Only thing that wasn’t mentioned here, and I may just be an idiot, but a note:
Do not hit CTRL+ALT+F2 while the freaking thing is still scrolling boot info. It should then go to a black screen. Hit CTRL+ALT+F2 then. I tried these steps 3 times before my stupid ass figured that out.