Hi Miamogue,
I'm assuming the individual control panels around the coach still light up.
There are only 3 wires to the control panels: 12V DC, ground, signal. So if your convenience panel still operates, all 3 wires are doing what they're supposed to do. That suggests that the backlight on the panel has failed. I don't think there's anything to see on the back side of the panel, other than 1 connector, but it might be worth take a look to see if something is loose.
If the back side looks ok, I'd suggest you call Heartland Customer Service at 877-262-8032 / 574-262-8030. Have your VIN # ready. If you bought the Landmark less than 2 years ago, they may send you a new panel for self-install, under warranty. If not, the parts dep't can sell you one.