Old AT&T TV C71KW-400 get ERROR 5107

Hello :

I have a box with AT&T TV logo in the system.

How Can i get upgrade ?

I think it's the firmware problem ...

I try press the red button 7 times .

update the system . 

I got stuck at the 3/4 part  , ERROR 5107 happened ...

Try to repeat it , but no luck ...

Please help.

Thank you