We will be running a mixed 2007 and 2013 Exchange environment for some time until we can get everyone moved over. As part of this migration, Exchange 2013 CU5 was downloaded since it is the latest, and schema / adprep / domain prep was all done from this. Then a pretty standard install was done after ensuring AD was replicated and healthy.
The install appeared to go ok, and a server reboot later it seems like all Exchange services are started and running according to the services console.
Next I want to log into the new Exchange Admin Center to eyeball some things and get familiar with it. One of my next tasks is to go in here and check the certificates, make a request, yadda yadda yadda, you know all the fun stuff now that this is installed. My issue is no matter what account I try to log in with, the EAC webpage just flashes / blinks...