Probably made a mistake on one of these steps so far.
Intention was to renew the server certificate on Exchnage Server 2010.
I renewed the exchange certificate in Exchange Management Console.
Error message in OWA is 403 - Forbidden: Access is denied.
I read that the certificate has to be imported.
Opened this MMC - Certificates(Local Computer) - so the MMC is connected to the Exchange Server.
Copied the renewed certificate in Personal\Certificate to the folder Trusted Root Certification Authorities\Certificates folder.
I left the old version of the certificate there for now....
Still getting the 403 error. Tried restarting the web service.