Can you also run the following commands in a terminal window (with your printer connected to the USB and turned on, before and after installing the PPA package of CUPS):
lsusb
ls -l /dev/bus/usb/*/*
ls -l /dev/usb/lp*
sudo /usr/lib/cups/backend/usb
ldd /usr/lib/cups/backend/usb | grep usb
lpinfo -v
Can you also run the following commands in a terminal window (with your printer connected to the USB and turned on, before and after installing the PPA package of CUPS):
lsusb cups/backend/ usb cups/backend/ usb | grep usb
ls -l /dev/bus/usb/*/*
ls -l /dev/usb/lp*
sudo /usr/lib/
ldd /usr/lib/
lpinfo -v
Post the output of the commands here.