@forest lin
It looks like your ambari agent might not be running.
1. Please try this:
# ambari-agent restart
2. Can you please check and share the ambari agent log ?
"/var/log/ambari-agent/ambari-agent.log"
3. Please check what all processes are already running on that Sandbox? It might be possible that few components might already be running but agent might not be able to show the proper status to Amabri Server due to some broker communication / OR agent down issue.
4. Please check the free memory available on the sandbox host:
# free -m
5. Also after restarting the ambari server do you see any error in the ambari-server.log?
.