apt won't remove/ purge installed package...

[Morgan Read <mstuff@read.org.nz>]

I attempted to install firewalld and firewall-config with ufw installed 
- perhaps not the wisest of moves - but, `apt install firewalld 
firewall-config` ran anyway, and then hung, together with the whole 
system and nil ssh access.

I'm now thrashing about in a rescue image with the system mounted on /mnt :
```
[RESCUE] root@vps-2493e43e:~ $ apt -o Dir=/mnt list firewalld 
firewall-config
Listing... Done
firewall-config/stable,now 0.9.3-2 all [installed]
firewalld/stable,now 0.9.3-2 all [installed]
[RESCUE] root@vps-2493e43e:~ $ apt -o Dir=/mnt purge firewalld 
firewall-config
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer 
required:
  gir1.2-atk-1.0 gir1.2-gdkpixbuf-2.0 gir1.2-gtk-3.0 
gir1.2-harfbuzz-0.0 gir1.2-nm-1.0 gir1.2-pango-1.0 ipset libipset13
  libnftables1 libpangoxft-1.0-0 libxft2 python3-decorator 
python3-firewall python3-nftables python3-selinux python3-slip
  python3-slip-dbus
Use 'apt autoremove' to remove them.
The following packages will be REMOVED:
  firewall-config* firewalld*
0 upgraded, 0 newly installed, 2 to remove and 0 not upgraded.
After this operation, 3613 kB disk space will be freed.
Do you want to continue? [Y/n] y
...
dpkg: warning: package not in status nor available database at line 1: 
firewall-config:all
dpkg: warning: package not in status nor available database at line 2: 
firewalld:all
dpkg: warning: found unknown packages; this might mean the available 
database
is outdated, and needs to be updated through a frontend method;
please see the FAQ <https://wiki.debian.org/Teams/Dpkg/FAQ>
dpkg: warning: ignoring request to remove firewall-config which isn't 
installed
dpkg: warning: ignoring request to remove firewalld which isn't installed
dpkg: warning: package not in status nor available database at line 1: 
firewall-config:all

                  dpkg: warning: package not in status nor a
vailable database at line 2: firewalld:all
                                          dpkg: warning: found unknown 
packages; this might mean the available database

                                               is outdated,
and needs to be updated through a frontend method;
                                                  please see the FAQ 
<https://wiki.debian.org/Teams/Dpkg/FAQ>
W: APT had planned for dpkg to do more than it reported back (0 vs 9).
   Affected packages: firewall-config:amd64 firewalld:amd64
[RESCUE] root@vps-2493e43e:~ $
```

Attempts at correction have included:
rm /mnt/var/cache/apt/*pkgcache.bin
apt-cache -o Dir=/mnt gencaches
dpkg --root=/mnt --update-avail
dpkg --root=/mnt --configure -a

Feeling completely lost, can anyone point me in the direction of home?

Thank you.
M
--
Morgan Read

UNITED KINGDOM
Em: <email:mstuffATreadDOTorgDOTnz>

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