Yesterday ubuntu issued updates related to DRM, packages:
ii libdrm-amdgpu1:armhf 2.4.99-1ubuntu1~18.04.1 armhf Userspace interface to amdgpu-specific kernel DRM services -- runtime
ii libdrm-common 2.4.99-1ubuntu1~18.04.1 all Userspace interface to kernel DRM services -- common files
ii libdrm-etnaviv1:armhf 2.4.
I'm having similar issues. Flashed an old image I had, everything was fine until I "sudo apt update && apt upgrade" reboot and now images aren't being rendered including terminal. Didn't think to try an image with 4xx kernel. Trying to get kubuntu up ,running and tweaked to run as a car headunit