Currently running Exchange 2010 on premise in a hybrid mode. We have have Azure AD Sync running as well. Almost all mailboxes have been migrated to the cloud, but we needed to keep a server on premise for management and internal relay. Recently an admin uninstalled the on premise Exchange server "accidentally" and is now having a difficult time installing it back into our environment. We are unable to manage DLs and mailboxes without this on-premise server.
Would it be possible to remove all links to the on-premise server and O365 and then try to install a new Exchange 2013 server, then re-establish the hybrid mode?
Any suggestions on how to get it installed back into our environment?