Black screen on boot

[LNXlady]

Then grub is not loading the kernel, systemd, etc.
You'll need to rescue the system, the easiest way to do this is with a live media.
You can either use the Maui install ISO, and install (use) the boot-repair tool:

Code:

sudo add-apt-repository -y ppa:yannubuntu/boot-repair; \
sudo apt-get update; \
sudo apt-get install -y --force-yes boot-repair && boot-repair

Or download the boot-repair-tool ISO and create a live USB with it:
https://sourceforge.net/projects/boot-repair-cd/

It didn't work exactly but it did improve things some. I used the dvd, it said it was repaired, I rebooted. Grub was no longer Maui themed but all my entries were there. However, it had added the radeon.modeset=0 back because it was still there even though I had removed it earlier. It booted and this time it DID let me change the resolution, so that is better, but it still isn't using the radeon drivers. It briefly flashed up something like, "No UMS support in Radeon Module" as it was loading. I rebooted and removed the radeon.modeset=0 to see if it would boot that way now but it just went back to the black screen. 
inxi says

Code:

Display Server: X.Org 1.18.3 drivers: ati,vesa (unloaded: fbdev,radeon)

 and the repair process gave me this pastebin url: http://paste2.org/7t0hW6ct
to post in case things still didn't work correctly.