I am not sure if anyone else has had this exact problem because there are quite of few "phone keeps shutting off" questions! But I dropped my phone on the ground last month and it started turning off on its own. It felt like it was trying to turn on but wasn't getting a charge. I took the battery out and put it back in and then dropped it on the table (I know I'm clumsy) but some how it started working again! So earlier this week I put it on the charger and it instantly came up with the download screen and told me not to unplug it. I was sure why it went straight to that screen when I was not trying to do that. So today I went to turn my screen on and nothing happened. The phone was maybe 85-90% charged and nothing. I have taken the battery out and it will start to load and then turns off. I have tried to reboot it and as soon as the yellow letters come up it turns off. I am not sure if it is the battery or if its the phone itself. I don't have a warranty any longer and it is the Samsung Galaxy S2 and the carrier is T-Mobile and the model is SGH-T989. Please help if you can! Thanks in advance.