Xorg.0.log is showing errors concerning no input driver being specified for the keyboard and mouse. It is showing the light DM login screen I just can't do anything at all. I can't switch out to a virtual terminal or move the mouse pointer. This is using kernel 5.2 because with 4.x kernels I can't get the GUI to load at all.

Additional Background:

I bought an ASRock DESKMINI A300W and installed a Ryzen 3200G/Vega 8 in it yesterday. I'm trying to install Manjaro Cinnamon on it. I almost was able to do this, but ran into a hiccup.

What I've done so far

Cinnamon install CD didn't boot to GUI after trying various options so switched to Manjaro Architect installer.
I completed the install on Manjaro Architect, installing a variety of kernels since I knew some might workable and some might not. I have 4.19, 4.4, 5.1, 5.2, 5.3 right now
4.19 / 4.4 kernels will not start lightdm no matter what I've tried. Xorg.0.log just shows it going through all the various modules from ati to radeon to fbdev/etc. and it seems to be failing each and then drops out entirely at the end.
5.2 kernel gets all the way to lightdm, and it looks perfect, but keyboard and mouse both do not work. Same occurs with 5.3 and 5.1. I can't even use the keyboard to switch out to a terminal.

I'm just trying to figure out what to try next. What's the easiest way for me to get to terminal in 5.1 and bypass lightdm loading automatically? I have read about editing the startup for grub but none of the posts I've seen this mentioned on matches with what I see in the configuration so I'm not sure exactly how to change it.

Xorg or wayland?

If wayland, then not sure what's going on, as it defaults to libinput, should have libinput be a dependency, and should just work.

If xorg, Arch and it's derivatives default to libinput anymore, so:

Do you have libinput installed (xf86-input-libinput)?

As far as bypassing, you'll want to boot into single user mode (runlevel 1), start networking manually if you need to install anything.

I think you need the evdev driver in Xorg.

I did have xf86-input-libinput installed, but earlier on when I knew less about what I was doing I tried installing catalyst and I had reinstalled some other things but not that one. Right now I'm running amdgpu and have experimental installed as well.

So I went and reinstalled xf86-input-libinput, xf86-input-mouse, xf86-input-keyboard and then typed startx and it loaded up and mouse was working. The screen is still flashing (black screen displays for 1 sec about every 30 seconds), so I have something else to fix I didn't mention but the direction you gave was very helpful to getting me closer to working system. Do you have any ideas on how I might be able to get rid of the flashing?

I read elsewhere about screen flickering that I should remove xf86-video-intel. I'm going to try a reboot as I just removed and screen still flickering

Does this look ok for what I have? (I am just using kernel 5.3 as I thought it might be worth checking if it eliminated the flickering, but it didn't).

inxi -SGxxz
System:
Host: rem Kernel: 5.3.0-1-MANJARO x86_64 bits: 64 compiler: gcc v: 9.1.0
Desktop: Cinnamon 4.2.3 wm: muffin dm: LightDM Distro: Manjaro Linux
Graphics:
Device-1: AMD Picasso driver: amdgpu v: kernel bus ID: 04:00.0
chip ID: 1002:15d8
Display: server: X.Org 1.20.5 driver: amdgpu,ati
unloaded: fbdev,modesetting,vesa tty: N/A
OpenGL: renderer: AMD RAVEN (DRM 3.33.0 5.3.0-1-MANJARO LLVM 8.0.1)
v: 4.5 Mesa 19.1.3 direct render: Yes

*Flickering much less at the moment without the intel driver, about ever several minutes now but not completely gone. Perhaps coincidental

*deleted

get rid of the ati driver. Can't say that'll stop the flashing, but it definitely should not be loaded for Vega.