Everything Works but the Controllers

For the past few days, I've had issues with my Xbox 360 S.

It started with turning off unexpectedly in the middle of using an app (ie Netflix or Youtube) - it would beep when it shut off as though the button had been touched. Sometimes I could restart and everything would go as normal. Other times it would shut down again immediately, taking a few minutes before booting normally. That went on for a couple days. Then it worked fine for the past 2 days.

I tried to use it today expecting everything to work. Everything did work -- but the green light around the power button never lit up. The console won't respond to any of the controllers. I'm left stuck on the Xbox Live login screen. The power bar's light is green and stays green and the optical drive still opens and plays all my DVDs.

I have no idea what is going on. Please, someone help me figure this out.