Bad battery, logic board, or something else?
I didn't notice any precursor trouble before one day, I couldn't turn my iPod on. It's an 80GB iPod Video with original parts.
At first, when I pressed the center button to turn on my iPod, it displayed the normal Apple logo, but the screen turned off before it finished booting (in that way where pixels linger and gradually fade away).
I connected it to a computer to attempt to recharge it. Upon plugging it in, it went into some kind of reboot cycle, where it would display the Apple logo for a few seconds (backlight went on, too), but it always died before it actually got to the OS, giving a blank screen for a moment before starting the cycle again. I left it plugged in for a couple of hours, and when I checked again the cycle had changed slightly. It now displays a battery with a caution sign on it for about half a second, followed by the Apple logo for about half a second before the screen shuts off (this all happens before the backlight even turns on now).
If I plug the iPod into a wall adapter, I get exactly the same cycle. If I remove the iPod from a power source and try to turn it on, the battery/caution screen flashes for a moment before the screen turns off, and it will not display anything after that if I try to turn it on without external power. If it's relevant, if I listen closely I can just start to hear the hard drive spin up, and it got slightly warm to the touch after leaving it connected to power for a couple of hours.
My first thought was a battery problem, but my iPod was running just fine for multiple hours the day before this happened. My second thought was a bad logic board, but I'm really not sure what that looks like. Any ideas as to what's going on and what I can do?