At the end of the procedure, GPU "GuiVM sys-gui-gpu" in documents, GuiVM Configuration | Qubes OS, it says "At this point, you need to reboot your Qubes OS machine in order to boot into sys-gui-gpu". I assume at this point sys-gui-gpu should be set to start automatically?
Mine was not, for what ever reason so i manually set it to autostart at system boot, but unfortunately this resulted in system failure. As soon as sys-gui-gpu booted my screen went black and i had to hard reset and boot with the "qubes.skip_autostart" GRUB boot parameter.
I am trying to figure out if i did something wrong or if my system just doesn't work with sys-gui-gpu and i should alternatively try the the "Hybrid GuiVM sys-gui" instead.