Lots of problems after replacing battery and hard drive. Help!

So the old 5th gen iPod (30GB) had stopped turning on at all. Previously it would occasionally show an error with a face with x's for eyes. I think it got left in the car too many times and froze and overheated. The center button also did not click

So I got another battery and a used hard drive and replaced them. I also found that the little pad under the center button had shifted over, so I moved it back to center.

After that, the iPod would not turn on with the new hard drive. I tried hooking it up to iTunes 11 on a PC but didn't get anything.

Then I put the old hard drive in there. Same thing, but I kept on trying. Finally I got it to turn on, but the battery was very low and the buttons and selector wheel didn't work. It also would not take a charge from charging cables that I know work.

I took it back apart and put it back together and now the wheel and buttons work, but I noticed it would freeze a lot when trying to play a song and it still wouldn't take a charge.

So I took out the battery and charged it on a universal charger and popped in the blank hard drive. Now it won't turn on again. I have it hooked up to iTunes 11 and nothing. And when I put the old hard drive in it also won't turn on nor is it recognized by iTunes 11.

Is there a step I missed or am I using the wrong iTunes or do you think the board is bad?

So I left it plugged in to the computer with iTunes open. The screen finally lit up with that face with x's for eyes and saying to visit www.apple.com/support/ipod. It then goes to a dark screen saying to wait that the battery is very low. This is odd as I had charged the battery to 4.23V (I meant to stop before 4.2V) and I don't feel any heat in the hour or so that it's been plugged in. It seems to be going through a boot loop with the blank hard drive.

So far, iTunes 11 isn't recognizing it.

So I put the old hard drive in and it started and even started showing a charge icon. It also had the green battery bar all the way full. But there was no response from iTunes so I tried another USB port. Well, the charging icon went away and didn't come back. I tried moving through the menus a bit and it froze, but the buttons still made clicking noises. Then the screen went black and it wouldn't turn back on. I disconnected and reconnected the battery and it still won't turn back on.

I've got it plugged in for now with another cable with hopes that it will start back up and this time connect to iTunes.

Well I left it plugged in and it turned on by itself. Again, I see no signs of charging. From what I can tell, it freezes if it's plugged into a computer and it also freezes and doesn't want to start back up if I force it to restart by holding the center and menu buttons for a while.

As far as how it works, it seems to work fine playing music, the music that's on it. I don't have any way of changing the music on it since if I plug it into a computer it freezes and then the screen goes black after a while.