So it charges correctly, but doesn't work. Is that right? If so, ya, I don't think there is any troubleshooting for the Pax just not working. But if you contact Ploom you should be able to get a warranty repair/replacement.
It's possible. Have you cleaned in thoroughly? Particularly the area at the top of the stainless steel vapor path, at the exposed end where the mouthpiece attaches. A resin buildup in this area causes most of the issues with the Pax. Cleaning with iso and an interdental toothbrush typically fixes it, but I'm not sure if this would help your issue.