How to bring another DC up with all roles when first DC is no longer available

ADC being Active Directory Connector for Exchange? If so, being an ADC doesn't make the server a domain controller also. If this is the case, you're out of luck as you've lost your only functional DC.

However if I'm reading that wrong and DC2 is definitely a full domain controller, then I think your problem lies in trying to use restore mode. You shouldn't need to. Instead, bring DC2 up into its regular windows environment, then follow the 'Seize FSMO Roles' guide found here: http://support.microsoft.com/kb/255504

Note: Ignore the 'Transfer' guide. It's not relevant for your scenario.

Edit: I just found the other question where you got the term 'ADC' from. This term is widely recognised as 'Active Directory Connector for Exchange' and not 'Additional Domain Controller' which I think is your usage. I don't recommend the use of acronyms that aren't widely used, as it often just causes confusion.