If the current HP Printer Assistant app won't open, try downloading and installing the most recent version of the app over the old one. From the link, download the HP Support Assistant installation. When prompted to confirm, run the installer and select Yes. Check if the app works after it has been restarted. Uninstall HP Support Assistant and then install the newest version from the HP Support Assistant website to fix this error:
How do I re-set up my printer? 1. Power the printer off completely.
2. While the power is off, simultaneously hold down the Menu>, Go, and Select buttons.
3. While still holding down the buttons, power the printer back on. Release the buttons when Restoring Factory Defaults appear on the display.
4. Allow the printer to warm up as normal.