I’ve also found that it takes a few attempts to start staging via edeliver after deploying a new release. I haven’t tried using bin start yet.
Which distribution are you running? Ubuntu 16.10 here.
I don’t know if this is relevant, but this rabbitmq issue shows that the error message about the sys.config file can be seen due to issues other than the file content syntax being incorrect: https://bugs.launchpad.net/ubuntu/+source/rabbitmq-server/+bug/653405
