[SOLVED] Debian11 update screwed my install; how to recover?

Hello,
yesterday I got the message to make a debian update, which I made with APT UPDATE then APT DIST-UPGRADE.

The PC froze during the night; this morning I tried to reboot, few errors appear and its weird.

First: the PC has a separate Windows SDD and it boot in it (and it goes into the internet)
It means only the Debian install on the separate HDD seems to be affected.

First: it stopped with a dark screen showing
Code:[failed] Failed to start Snap DaemonI cannot imagine the snap was on it. So, I removed it (by starting debian in recovery mode)
APT REMOVE SNAPD

in the recovery mode, the APT UPDATE dont work with the usual errors
Err.. could not resolve deb.debian.org and others

by booting in a previous debian install from the Grub menue, it shows the errors
Failed to start Hostname Service
.. GNOME Display Manager
.. LSB: exim Mail Transport Agent
.. GNOME Display Manager

Any advice how to recover is welcome.

UPDATE: from here "Failed to start GNOME Display Manager" https://forums.debian.net/viewtopic.php?t=150221
I see the result of Code:df -hCode:..
/dev/sda2 28G 26G 0 100% /
..It means the root, for any reason, went full up..?
Now I will have to find how to clean it.