users cannot access O365 email (white blank screen)

I was upgraded to O365 from Live@EDU a little while ago, but since the upgrade my users cannot access their email.

I dont know whether the issue is caused by the upgrade of whether it is something else?

I also have multiple domains too, I am not too sure where they have come from??  I have an onmicrosoft.com domain and also my internal domain name in the cloud, very confusing.