Backstory - Both our servers have evaluation versions of server 2012 r2, and you can't upgrade and activate a domain controller. I figure no problem, I'll activate and update my server that has our TrendMicro security solution on it (it uses the SQL database), promote it to a domain controller, transfer FSMO roles, demote the main domain controller, upgrade and activate it, re-promote it. It would solve having our backup domain controller, and having to setup a spare workstation just for the domain transfer stuff.
Well, little did I know, it's against Microsoft best practices, and it also broke SQL Server. From my understanding, when you upgrade a member server to a domain controller, it removes any of the local SQL accounts. Now I'm stuck trying to resolve this as I have no rollback and no one here knew any better when they advised me...