by jibz » Oct 13th, '20, 09:00
Only a page in a link in the thread mention it, so I add here a hint :
Root partition should not be read only.
On the line where init=/bin/bash is, check if 'ro' (read-only) is not present, or remove it.
After, it is possible to check if still read-only with the command :
mount -l | grep " / "
If it mention read only, remount with :
mount -o remount,rw /
Then, it will be possible to change root password.