…just so I don’t lose them…
dmesg spews out messages a Linux kernel has been issuing… which should also appear in /var/log/syslog (h/t Rod Norfor)
/var/log/upstart/SERVICE.log has log messages from trying to start a service SERVICE.
/etc/init.d should contain what looks like a generic sort of file, filename SERVICE, with the actual config file that contains the command you want to start the service in a file SERVICE.conf in /etc/init.
To generate the files that will have a go at auto-running the service, run the command update-rc.d SERVICE defaults.
Start a service with service SERVICE start, stop it with service SERVICE stop, and restart (stop if started, then start) with service SERVICE restart. Find out what’s going on with it using service SERVICE status.