Screen goes/stays black after hitting the A button on startup screen

When I start the console, I get the "Health and Safety" screen, then a message comes up telling me to hit the "A" button. Once I hit the button, I hear the "button press" noise and the screen fades to black. After this, no matter how long I wait, I get no sound and a solid black screen. I've tried unplugging the console from its power source and plugging it back in, multiple restarts, and even different controllers, but to no avail. The Nintendo customer support agent with whom I spoke said that it sounded like a hardware issue, but I have no idea where it would originate from (given that I'm getting video AND audio at startup). Any advice?