interrupted do-release-upgrade

[Stuart McGraw]

Hello all,

I was running 'do-release-upgrade' (in a terminal window) to upgrade my 17.10
system to 18.04.  The download phase had finished, the install phase was in
progress (I think) and I was responding to a debconf prompt about a modified
config file when I accidentally hit ^C and interrupted it.

Some googling suggested the upgrade might be running in a 'screen' process
but 'screen --list' reports screen is not installed.
Rerunning the do-release-upgrade command says no new release found.  Running
   # apt-get install -f
   E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)
   E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?
I have a "bionic" process running but
   root     20565     1  0 111581 78132  0 15:16 pts/1    00:00:07 /usr/bin/python3 /tmp/ubuntu-release-upgrader-ak_28mh_/bionic --mode=server --frontend=DistUpgradeViewText
but I don't know if that is useful or not.

Google results were varied, some sounded sketchy, a lot pretty old, so I thought
the best thing would be to ask here.  I am new to Ubuntu and this is my first
time doing a release upgrade.

Thanks for any advice.