Filesystem Size Used Avail Use% Mounted on
/dev/loop3 50G 49G 1.1G 98% /var/lib/docker
Docker image is full, this is usually the result of a misconfigured container.
This is usually a flash drive problem, recreate a new flash drive using the USB tool or manually and before restoring anything from the backup see if it boots.
Not clear from your previous answer if you had any VM already configured, if you don't, or it's not important, delete libvirt.img and create a new one, any configured VMs will be lost.