Emax

Hello boys, I've recently bought an EmaxHD.
The previous owner said that everything was OK, and it's really in a 
perfect condition and merely used, but surprise surprise...when I try 
to sample I can't hear nothin' comin' out from the sample input!
So there are two possibilities: one, who sold it to me didn't tell 
the truth...second, somethin' inside has been damaged during the 
shipping.
Is there anything I can do to make it work again?
Is there any place where I can find a schematic?
Hope someone can help me!
 
Lorenzo