Keypad Malfunction; Modes lights won't change

The modes no longer light up on my security system; first generation, keypad. The modes change on the controller base station fine; both the light color and announcement are correct. But it's unnerving to not see the proper lights change on the keypad at the door! I've screwed around with this for two days; my cell phone has been off and no several times, for example, I think the keypad is probably bad. John