I found a solution to make the reboot.
I had uninstall libreoffice packages with :
sudo -s (& password)
apt remove libreoffice*
The package libreoffice-base doesn't want to uninstall.
So i do:
nano /var/lib/dpkg/status
and remove all entries about the package libreoffice-base
and save.
I changed "/etc/apt/sources.list"
with
"deb
http://deb.debian.org/debian buster main contrib non-free
deb
http://deb.debian.org/debian buster-updates main contrib non-free
deb
http://security.debian.org/debian-security buster/updates main contrib non-free
and make a new apt update & upgrade & full-upgrade
So debian 10 is installed.
I go to /etc/systemd/system.conf
and change DefaulTimeoutStopSec=90s
by DefaulTimeoutStopSec=5s
and save
i enter : systemctl daemon-reload
and
reboot
The system reboot well.
BUT WHEN IT START AGAIN, it stop to "gemian booting" image.
ANY IDEA ?