Immediately overheating/lack of ventalation on startup

Hey all, I have an Xbox 360 E that I've always taken good care of. One day, after 5-6 hours of playing, the fan got very loud and blasted loud for about a half hour until it shut down due to lack of ventalation. I turned it back on and had no problems for another 5-6 hours until the fan got loud and it overheated again. The console had NEVER over heated or powered off before this. This continued to get worse every day, with the time it's starts over heating becoming earlier and earlier. I should also mention it seemed the fan was permanently louder. A month later it got so bad I couldn't even play for 5 minutes without overheating, I had to resort to putting something cold from the freezer next to the Xbox vents, about 3 inches away or I couldn't play. The fan wouldn't be as loud with the cold cans next to it. I was able to play 7-8 hours as long as I had something cold by the Xbox, then that started becoming less effective. As the days went on I had less and less time until the console overheated. It is now to the point that when I hit the power button on the Xbox, it goes green for 1-2 seconds, then immediately flashes red, the fan blasts and powers down in about 5 seconds, can't even see the 360 startup icon it powers off so quickly. Flashing red is the lack of ventalation/overheating indicator for the Xbox E, but it is not overheating. It can sit off for a month, I power it up and it shuts down due to lack of ventalation immediately in 2 seconds. There is nothing blocking the vents, it is in an open area elevated off the carpet. The power brick is Orange when off, and turns green when I start It and stays green until it powers off. It is not red ring of death obviously, the Xbox 360 E isn't even supposed to get red ring, the power button flashes red, it is not a solid red. I opened it up and the Xbox is very clean, minimal dust. The thermal paste was dry but could that really cause it to shut down immediately..? Wouldn't I at least be able to get to the dashboard? It was almost powdery dry. I should also note this went on for about 2 months until it was unplayable, the Xbox never even got hot it always felt normal temp when it would power down, sometimes on the colder side. I've seen many posts relating to this instance without definitive answers so I'm hoping to fix my problem so others with the same problem and no answers can rest assured.. :) Any help/input is greatly appreciated, thank you!