I put a new battery in my 2 year old 3gs, showed 56% when i booted it back up and it runs fine, mail, text, yada yada. On the phone for a hours or so and i see it hit 20% so i plug in the charger in, i keep talking on it. All the sudden the phone dies, blinking red battery and the chargers plugged in. So i leave it plugged into the charger and stop using it, still blinking playing like its not charging a hour later, i unplug it, go to bed. Wake up and plug in the charger and after 2 hours no change. Well today i decide put the old battery back in, it charged fine was just worn out. Well the apple logo pops up after installing the old battery, some times the little wheel spins sometimes it don't, the power button don't work, the only way to get it to turn off is to hold home and power for a few secs. I decide to restore it, i get in into restore mode by holding the home and plugging in the usb, itunes sees a phone and says it will restore it. It goes through its paces, apple logo on my phone and a status bar is filling up, it says its done restoring on the PC side, status bar fills up and disappears but the logo is still there phone side, then a message pops up in iTunes, "iTunes could not restore the phone because a error occurred", that's it, no code, apple logo and a spinning wheel. Sorry for the long post.