Here is a great tip for Apple iPhone 3G users who need to power their device back on.

So if you have an iPhone 3g you've probably noticed that the phone sometimes shuts down and doesn't turn back on unless you plug it in no matter how long you hold down the power button or how full the battery is, well I've got an easy fix for that, all you have to do is start holding down the power button then after about two seconds begin holding down the home button and the phone should turn on a few seconds later, hope this tip helps.