Jim, please use orm file that I attached to this post. As in that one from master there were some code changes as well.
Regarding this serialization issue, do you get process definitions from Guvnor? If so, do you run the one that comes with 5.3? And do you run them in the same server if not make sure you run them on the same jvm version. And any way rebuild you packages in Guvnor prioor to running them in console.
HTH