I locked my door with the keys inside using the keypad on the outside. I went into work and came out 2 hours later to find that the keypad is no longer working. I can see a led light on showing it has power but the pad does not work. It is also during the day so I cant see if the numbers are lighting up. I press the last two locking buttons and I do not hear a locking noise. It is for my 2004 f150. does anyone have any suggestions?