Can you try the http://127.0.0.1:8080/ address and see if you can access Ambari? The 8000 port is for Hue, which is an interface that allows you to interact with Hadoop through a GUI. You may want to try and ssh into the sandbox to ensure Hue is running. This can be accomplished with a service hue status, to check the status. You can execute a restart by executing service hue restart. I hope this helps.