Xbox 360 S turns on, but no green ring appears.

I keep my 5 month old Xbox 360 S in a well-ventilated area and treat it like a baby. It's actually never moved from the spot, save for the time I had to add the 250 GB hard drive which was well over 3 months ago. I install updates whenever they pop up and for the record I purchased this brand new from Best Buy.

My issue came when I turned it on as per usual and it powered on, but the rings never came on; just the green dot in the middle. I checked the brick as I've had a power supply issue many moons ago, and I have a green light. So after unplugging the unit several times, switching the hdmi cable and ports on my tv as well as removing the 250 GB HD and powering it up without it, I'm totally confused. It's also noticeably quieter than normal when it starts up.

I wouldn't be as upset if, God forbid, I had a red light, or some type of symptom that's actually populated online but my situation seems to be quite unique and buyer's remorse (buying anything from Microsoft, period) is starting to kick in. Any help/assistance/hug would be great; a solution would be greater. Ultimately, I hope there's help out there and if there is, I'd gladly be the guinea pig.