Why does the display rotate through various test patterns on startup

When I power on the TV, all I get is a set of rotating test pattern screens. It toggles between the following screens

* solid blue

• solid red
• solid green
• horizontal color bars (wide bars of red, green, blue, and white)
• vertical color bars ( wide bars of red, green, blue, and white)

I’d like to fix this myself, but I’d need to know how to diagnose the issue. Could it be firmware? Do I need to purchase replace parts?