netdom query fsmo
and make sure all the roles are listed for ROHNSERVER – also run this command on the other DC and if the roles are different then you may well need to forceremove that – ensure active directory has been cleaned of all references to dc’s that aren’t dc’s, dns and AD sites and services – then you should be able to rejoin the server to the domain and repromote it
Go through this carefully and then be very careful using adsi edit:
How to remove data in Active Directory after an unsuccessful domain controller demotion
http://support.microsoft.com/kb/216498
dcpromo /forcemoval <-- do this first then follow the 216498 paper