Tablet Diagnostic Tools

We get reports from the field indicating something is broken.  What are some steps to see how things are working?

1. Check Data Usage
   1. Settings->Data Usage
      1. Displays a graph of total data usage.  There is a list of applications below showing who is using what data. 

Notes:

Discovered two biggest users on the VR tablet were Google Play services (137MB) and Google Play Store (11.3MB). Why?