Sometime you can get error while connecting to exchange Powershell with the error :
Connecting to remote server [Your Exchange Server] failed with the following error message : [ClientAccessServer=[Your Exchange Server],BackEndServer=
And on the ECP Or OWA there is a white page or error about service down . although all the services are up and running .
This can happen because the Exchange Back End web site in IIS lost its certificate, re-bind the right certificate to the site :
Open up IIS Manager --> Right click on the Exchange Back End and click on Bindings --> Double click on https and ensure that there is a correct certificate has been selected
run : IISRESET from CMD (running as Administrator) and try again !