Well, I just sent my N800 back after one week due to this problem. Last night, I was watching a movie with my N800 plugged in, when it suddenly died again and would not turn back on. I even left the battery out for 8 hours and tried the resurrection procedure numerous times. The charger WAS NOT EVEN CHARGING the battery, as it was not the slightest bit warm. (It usually gets quite warm when I'm charging the N800 without using it at the same time)

I called Nokia about the problem and they said that I should return it to the vendor.