Self hosted Instance - Connection refused

Hi All,

Just wondering if anyone has any doco for troubleshooting logs of a Self hosted instance?
I am about to jump into a client who have updated their dev instance to UTAH but since doing so they cannot access the dev interface. Error is connection refused. 
I suspect its going to be something like a Java update issue but I don't yet have access to the system(And I have not worked on a self hosted instance before) so I am trying to guide the team as to where to look for logs, Unfortunately without HI access I am not finding any useful doco online where I can give specifics to the team as to where to look.

Does anyone have any good reference material for self hosted troubleshooting docos or videos?

Would be awesome if I could send them some specifics about file paths for app logs\java logs