iPod in a constant state of charging, post-battery replacement.

I recently cracked the screen on my 30 gig iPod Video, and decided that it was time to swap out the slowly dying battery while I was in there.

Both repairs seemed to go just fine, and as soon as I plugged in the iPod, the Apple logo popped up, and all seemed well.

I let it charge overnight, to make sure the new battery had a good base. However the next morning, it said it was still charging.

I unplugged the iPod for a moment, to see if it was a connection thing. It gave me an estimated 50% battery charge.

So, I plugged it back in, restored and updated the iPod through iTunes, re-synced it, (which went fine,) and gave it all day to soak up power. but I've still got the little battery-and-lightning-bolt charging screen.

I haven't disconnected it again; I'd like to avoid stressing the battery by pulling it off the charger again before it gets a good initial charge. So I don't know how full it thinks it is right now.

Is this likely a bad battery? I just received it in the mail from iFixit yesterday. Could it be something else? It had no such charging issues before the repair. The battery life was just meagre.

Oh, and I've considered trying the old battery again, to see if it'll take a full charge. I just wanted to see what other options there were before I cracked it open again.

Thanks in advance!