I clicked the sleep button on my iPhone so that I could take the bumper off, and it's remained off ever since! it had just finished charging off the mains, so i know the battery isn't flat. I've tried all kinds of button combinations; holding sleep/home individually for 10-15s holding sleep/home at the same time for 10-15s each of the above while plugged into my mac, and also when plugged into the mains. i've also tried loading itunes, and plugging in the iPhone while holding the home button. i've only had the thing a couple of days, haven't really taken it out of the house, but this has happened. any ideas? it's a 32 GB one, if that's at all useful.