I don't know that I've ever run across a flow chart for diagnosing an EM game. That's more of a software technique so maybe it only applies to SS games that do most of their math in software.
Score motors from any manufacturer generally have a number of switches wired in parallel that when closed will cause the motor to run. The first step is to identify which of those switches is closed when the motor won't stop running. Once you've found a closed switch figure out if it's closed because it's bent, shorted or because the relay or other device that activates it is stuck on. If the switch is closed because some other device is active and closing it then you need to start over and figure out why that device is active.
There are lots and lots of topics here that talk about running score motors. That is an often overlooked resource.