Chosen Solution
My iphone 3g won’t turn on it has the sleep button and home button not working. and it worked fine until it ran out of battery. then i plugged it in and it showed the charging sign, I left it there for 40 minutes and it was still there. after that i unplugged it and tried a different power source and nothing showed up. i tried leaving it charging over night and still nothing.
you will have to change the battery iPhone 3G Battery Replacement