Comment 4 for bug 1561093

Regarding the instructions to add the PPA, they are on the overview page (https://launchpad.net/~hardware-certification/+archive/ubuntu/public):

“You can update your system with unsupported packages from this untrusted PPA by adding ppa:hardware-certification/public to your system's Software Sources. (Read about installing)”

First, let's try to see if the package installation was successfull or not:

1. type :
    plainbox --version
You should see `0.26`
2. If 1. was successful, try running `checkbox-cli`.

If not, you may have to uninstall both `python3-checkbox-ng` and `checkbox-ng` packages before retrying to install the latest version:

sudo apt-get remove --purge python3-checkbox-ng checkbox-ng

Then try installing the packages again.

Hope this helps!