This is most likely due to the video cables not being properly connected. Please remove and reattach the video cables, taking careful note of the color of each plug, and the corresponding port you plug it into on the TV. It is also important to make sure that you are using the proper cables for the ports that you are attaching them to.The most common cables types are outlined below for clarification:
Composite: A series of one video cable (Yellow) and two audio cables (Usually Red and White).
Component: A series of three video cables(Red, Blue and Green) and two audio cables (Usually Red and White)
HDMI: A single audio and video cable with a rectangular plug on either end..