Can't run Exchange 2013 EMS - Access Denied: migrating Exchange2003 through Exchange2007 to Exchange2013

We are in the process of migrating a client from SBS2003 to Windows2012R2 + Exchange 2013. The domain and shares have all moved to the new server, but the Exchange is on a Windows2008R2 staging server with Exchange 2007.

We can't run the Exchange 2013 EMS - the error is below.  We can't login to EPC either, as it also says access denied.

VERBOSE: Connecting to server.domain.local
New-PSSession: [server.domain.local] Connecting to remote server server.domain.local failed with the following error message : Access is denied. For more information, see the about_Remote_Troubleshooting Help topic.
At line:1 char:1+ New-PSSession -Connection URI "$connectionUri" -ConfigurationName Microsoft.Excha ...+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+ CategoryInfo             : OpenError: (System.Manageme....RemoteRunspace:RemoteRunspace) [New-PSSession], PSRemotein
  gTransportException+ FullQualifiedErrorId : AccessDenied,PSSessionOpenFailed

We have already:

• Run the EMTshooter - which finds the same error but says 'Unknown Error'.
• Checked Timesync
• Rebuilt OWA & EPC ISS folders 
• Lots of other things - but without effect.

Can anyone suggest a way forward?