Toshiba LCD 49L310U shows Toshiba "splash screen" + sound, no picture

My Toshiba LCD 49L310U has been working perfectly fine for about five years, and all of a sudden this morning when I went to turn it on, everything looked to be as normal. The Toshiba DTS Surround splash screen shows up just fine, and then when it should be loading the TV program, the screen goes entirely black and all I hear is the sound. Can’t get anything to show up on the screen. I’ve moved the HDMI input (but have not changed the HDMI cord, so maybe that’s a possible solution?), and have unplugged the TV for 10 minutes and then plugged it back in, to no avail.

Are there any other options for me to try? Could it be as easy as an HDMI cord? The HDMI cord being used is the one that came with my Comcast set-top box, so I don’t know if that makes it more or less likely to be the issue.