My iPhone 4 won't turn on, tried everything?

I just got done texting and then I go in to close my phone my pressing the upper right button, all I see is the apple logo flashing. It never turned on again. I've tried everything plugging it into my wall outlet, laptop. holding power button, then holding square button then holding both. Took it to AT&T they don't know what's wrong with it, and the nearest apple store is 1 hour away. AT&T said my warranty is outdated so what do I do!? It never touched water or hit a hard surface??