My iPhone will not startup!

I have tried everything on this website and nothing is working! My phone stays on the apple icon screen constantly. I cannot get it to turn off with the power button, I have to hold the home button and the power button in at the same time to get it to turn off, then most of the time it comes right back on, to the apple icon of course. I plug it in to itunes and when the computer does recognize that there is something plugged in, then itunes error message says: "The iPhone software update server could not be contacted". Every once in a while it'll show the empty battery, like it does when the battery is dead. It also gets abnormally warm. It has never been wet at all, It was in an otterbox from day one. It has been dropped a couple times, but not hard. PLEASE HELP this is my fourth one!!