DocumentRoot /home/user/public_html
PassengerStartupFile index.js
PassengerAppType node
PassengerAppRoot /home/user/nodeapp
This how you set up the startup file of the cpanel application manager. I don´t understand the difference and this is my main problem to make it works.
DocumentRoot is related to the directory where your domain is pointing if you are using cpanel there is high chance is public_html.DocumentRoot /home/user/public_html, passenger AppRoot is where your app is located could be public_html or another route, that´s depend totally of you, a good hint is your application manager configuration in cpanel, it´s the same folder you setup, and user in the example is your user cpanel name.
If you change the code in this way and still is not working, I suggest contact technical support.