Recovering from USN Rollback When reverting to a VM snapshot of DC

I made a mistake and reverted to a snapshot of my Primary Domain Controller while trouble shooting a problem. The back up Domain Controller took over primary role while I rebooted the server and when the revert was finished there was a conflict and I had USN rollback issues. My primary DC that I reverted recovered the Active Directory and stopped netlogon so nobody could logon to the server. The secondary lost connection with the primary and no longer had a populated active directory. I took down the secondary DC thinking it was causing conflict but that moment had passed. This happened yesterday during down time so I restored my primary domain controller from my netapp snapshot to a time when it was the primary and had no conflict. I power it up while leaving the secondary offline.

Things seem to be operational on the primary now but the secondary is shutdown thinking it has the primary role. How can I bring this back online and take the secondary position again? If I power up as is will it recognize the primary and take its place or do I have to do an unauthoritative restore and force it to talk to the primary? Last couple of options is to restore the secondary DC with the same time stamp from netapp or demote/rebuild the secondary server, strip the meta data from the primary and rejoin?

whats the best/easiest/less risk thing to do? other options?

Thanks,
Rob