My commute consists of 15 min bus ride and a 15 train ride. My phone had no problems up until today. I was using my phone on the bus checking email and reading the news. I got on the train where I get no signal and when I took out my phone when I got off it was dead. I know that I had charged the battery all night so juice was not the problem. I also didn't drop or bang my phone nor spill liquids on it. I got back home and contacted Samsung but I decided to investigate if other people were having this same problem before I sent it in and found these posts. For a second, I saw the Google, charging, and Nexus icon but then it died again. I've read in quite a few posts that even if I send it in Samsung will not admit that there is an error. Heating the phone before trying to turn it back on also did nothing.
I will add one thing, however. I recently downloaded a graphic intensive game from the Market and noticed that my phone was getting really hot and slow and a slight acrid odor was noticed. Maybe this had something to do with the problem?