To see any VERY useful Kernel Boot Messages on Screen do:
nano /media/boot/boot.ini
then search line 9:
setenv condev "console=ttyS0,115200n8"
change to:
setenv condev "console=ttyS0,115200n8 console=tty1"
now enable Multi-User Console this disable graphic Lightdm Login Manager
systemctl set-default multi-user.target
Now you can debug all again.. be happy