Back in the 60s (as a junior tech) I used to grind the tops off of TO-3 transistors like that to analyze the failure modes. I am not familiar (or don't remember) base-emitter shorts like that, but I expect with the top ground off you may see visual evidence of the base-emitter fault. The base collector junction appears intact (?). The 100 ohm resistor in series with the base makes that an unlikely path for over current failure, but perhaps a reverse voltage breakdown(?). Base-emitter junction breaks down with about 7V reverse.@CJ here's the part:
And @JohnRoberts I just measured the transistor and it shows 100 ohm in both directions base to emitter and a normal continuity between base and collector.
JR