Common carriers such a UPS seem to be treating packages rougher and rougher as years go on. We have started to notice more reported problems with S4 timers than we used to. Apparently the ribbon cable connection between the main circuit board and the face plate can be dislodged if the box is dropped or jarred severly. Symptoms include problems with the front buttons, failure to clear or recognize commands etc. Remove the small phillips head screws on either side of the case. Lift the case cover off and you will see the ribbon cable connection on the main circuit board. Remove it, replace it and make sure it is snug. Put a dab (really small amount) of "goop" or other silicone based glue on either side if you want to make sure it is not coming off again.