there's a single exchange 2013 server and the ssl wildcard certificate in use expired so install a new wildcard ssl certificate and assigned to services.

outlook is working but unable to sign in to OWA or ECP, after entering credentials and try to sign in the page refreshes and comes back to the sign in page (looks like in a loop). no errors, if try to login with incorrect credentials then will come up with error.

there was a missing Exchange Auth certificate error so created a new Auth cert and assigned to SMTP.

verified that correct wildcard ssl certificate is bind to default web site within IIS

Thanks in advance.

Hi 

First i would recommend you to check the event logs
Then Run https://testconnectivity.microsoft.com/ and see what error you are getting
Check the bindings in the iis
({http port 80 *}{http port 80 127.0.0.1}
{https port 443 *}{https port 443 127.0.0.1})

In addition to all the above you can check below steps as well mentioned in the article

http://exchangequery.com/2015/05/13/exchange2013-unable-to-access-ecp-encounter-500-unexpected-error/