Need Help - cannot get AT&T Uverse to connect to Samsung Smart TV

I just hooked the TV up and all of the smart TV apps work great.  When I try to connect to the AT&T Uverse box via a HDMI cable (like I used on my previous TV), it keeps telling me that there is no power.  What is odd os that when I am in the connection guide, if I reset my box, I can see the screen where the Uverse starts to reboot (the 3 dots), but before it finishes, the screen goes blank.  Iy is super frustrating.

The Samsung is a Q08A model

Thanks for your help!

Dave