In that setup the regulator controls the 12v feed to the field windings, the other side of the field is grounded. So unless some sort of short inside the alternator some how shorted the stator to the field I dunno. I guess a continuity check between the BAT and the FLD terminals would tell that tale.

Usually, there is a fusible link internal to the regulator to prevent a short in the green wiring from doing this sort of thing, at least with the original style mechanical regulator, not sure about the electronic version of this regulator though.

I'm thinking some sort of short in the wire, did it get pinched under the valve cover, DAMHIK, lol.