originally posted on https://askubuntu.com/questions/1103218/amd-card-causes-black-screen

So I just installed ubuntu 18.10 yesterday and know practically nothing about it. But whenever I booted it, it would either work, or go into an infinite state of blinking a white underscore on my screen and all I could do is turn off the computer.

Now after installing amdgpu-pro drivers for my rx 550, it would not boot at all, and gave me an error message:

vgacon disables amdgpu kernel modesetting

I heard it had something to do with "nomodesetting" being enabled in my grub config thing, and although I know how to get to it and delete nomodesetting, that causes my screen to go black permanently (that's why I enabled nomodetesting in the installation process, even the install usb would get the black screen without it) The nomodesetting thing comes back after I turn off my computer, so I would think the crash stopped the settings from saving.

Most of the forum posts I found related to this are for linux users who aren't complete noobs at linux, and I don't understand much of the terminology or software. I can access the grub boot menu and the command line, but that's about it.

So can anyone tell me how to fix this problem in a way I understand?

I don't think it will help that much, but here are some of my specs:

Intel Pentium G4560 CPU
AMD radeon RX 550 GPU
1TB HDD