My iPod 2nd Gen, Model MB528ZP, running iOS 4.2.1 has recently started having serious battery related issues, along with other problems.

On idle, I get about four hours of battery life before it is completley drained; the top left hand corner is producing heat (not rediculous amounts, though definitely noticable); and the wifi can't "see" any networks.

I've tried reinstalling the iOS, though that didn't help at all. Also downgrading doesn't appear to work, though that may well be the .ipsw files I have.

What could be causing this excess heat, the broken wifi and the short battery life? As far as I can tell, they are probably related: all tree issues started at the same time, though not after a drop nor an update.