Can't watch U-verse TV

We Bundled TV, Internet & Phone. Phone woks fine, have access to the net but the TV screen is FROZEN on " U-verse is not available at this time. Please try again later." Blue tab at lower right corner of screen reads " Restart Receiver". The connection for this service is fiber optic & the AT&T equipment provided is Arris set top box model # VIP2262 V2 & the gateway modem tower is BGW210. Does anybody have any idea how to help us out? This was installed Tuesday 12/18/18 & the TV was working fine when I turned it off & went to bed. Wednesday morning, turned TV on to the FROZEN screen message that is still the only thing visible. Thank You to anyone who can help.