Running a systemd service as a user other than root!
To show the problem use
journalctl -xe after you started the service.
You don't need a bash script, put this in your service file:
There is no need for
ExecStop, systemd will stop all child processes. You can view the output with
journalctl -u amos.service.
I think you want forking instead of simple. Simple assumes your process doesn't exit, so when it does, it calls the process dead.
You probably want to remove the amos_service.sh script and put it's functionality into the amos.service.