iPhone 3G will not charge, stuck on "lightning bolt" low battery screen
Yesterday I used my iPhone all day, like normal, until the battery got so low that it died at maybe 10pm. I plugged it into the charger that night, but this morning, all that's on the screen is a big empty battery with a sliver of red and a lightning bolt. If I unplug the charger, it shows an electrical cord + a lightning bolt for about 5 seconds, then it turns off. I've tried multiple cables and multiple power sources (charger, pc), but it will not change.
I was able to get the phone into DFU mode, and I restored it via iTunes normally, but when it rebooted and said "wait for the iphone to show up in itunes to set it up", it just went back to the battery screen and never showed up in iTunes.
Any ideas?
iPhone 3G 8GB 3.1.3, Windows 7