It's very possible that someone dumped some soda or coffee in that area. The 360 System ShortCuts are very easy to pull apart and work on. Each set of buttons is on a sheet. Pull off the sheet of buttons and clean the contacts (very easily seen, once the sheet of buttons is pulled off) with isopropyl alcohol, or even light soap and water. If you're familiar with the Radio Systems Millenium console ON & OFF buttons, same concept.