• Install mythbuntu from DVD
• Enable the MythTV and Mythbuntu repositories in the Mythbuntu Control Center GUI
• Run (as root): apt update
• Run (as root): apt upgrade

For some combinations of hardware and software versions, the display that MythTV is using can become “deactivated”, usually due to the actual hardware display being switched to another input (as is common for TVs, switching to a different HDMI port, etc…).

To reactivate a display:

#!/bin/bash
SDN=":0"
VDN="HDMI2"
xrandr -d ${SDN} --output ${VDN} --auto

… you might have to find the values for SDN and VDN from .config/xfce4/xfconf/xfce-perchannel-xml/displays.xml

Technical Information Repository