While trying to perform an update on my second console, I get this error message 351F-0000-0080-0300-807B-01F7 while trying to perform the mandatory system update. I haven't been using this console in a while after I recently got a Gears 3 LE Console a few weeks ago. I recovered my gamertag on the new console after I received it. This older Xbox has been working perfectly since I switched.
I have performed a Cache clear, reset my router,and unplugged any unnecessary USB devices such as Kinect and additional memory.
My other console, with the update already installed, works fine and I have connected to Xbox Live, participated in a Party Chat, and played Gears of War 3 without any problems.