If you're getting 500 error which means the hotfix was not applied properly and you missed something. Only option which I think is to roll back the update and you can copy all the backup folders and the re-apply the hotfix. If you search forums you will lot of users had same issue and that is because they missed something while applying the hotfix.
I appreciate the quick response. I'm not sure how to rollback an install that is over a year old. I'm Googling now but if you have any tips please let me know.
Rolling back the changes means you took the backup of few files/folders when you applied the hotfix a year ago. Can you please let me know if you remember which Section in APSB13-03 have you followed in your server?