iPod completely dead after battery swap

Hello friends!

I’ve had a 80GB iPod Classic (thin) for 11 years now and absolutely love it! People remark on how they can’t believe I still have one of these things every time they see it. But, the battery got bad enough that it would only last about 30 minutes before dying, so time for the swap!

Unfortunately, after completing it, my iPod is completely dead and completely unresponsive now, and despite searching for hours on iFixit and other sites, I cannot for the life of me figure out what I did to cause it!

So here’s every precise detail I can give:

1) While disassembling, I was prying apart the two halves of the iPod and snapped the cable connecting the headphone jack to the motherboard. I purchased an entirely new assembly and replaced it before trying to reassemble and restart (I figure that’s unlikely to be the problem, but full documentation here!)

2) I moved the logic board assembly (complete with screen, click wheel, charging port, and HD all still intact. I did not disconnect any of them from the logic board) into a new face plate while I had it apart. (I didn’t drop or snap/break anything in the process, nothing else to make me think this is where the problem originated)

3) Of the two cables I disconnected in the repair process (the battery and jack/hold button cable), I’ve disconnected and reconnected each of them at least a dozen times. (Given I’ve carefully redone them, and have not otherwise damaged them, I figure this is not the problem either)

4) I noticed after initially trying to power on that I accidentally had purchased the “thick” battery even though I have a “thin” model iPod (my biggest hunch: could the thick battery have fried my logic board?). I plugged my old battery back in for troubleshooting since I know it was working (albeit poorly) prior to disassembly, but iPod is still completely dead.

5) iPod does not respond to any inputs whatsoever. This includes hold button on/off, menu/center button hard reset, or plugging into a power source. The screen never comes on or flickers. When plugged into power source, the hard drive does not spin/whir/click, indicating it’s not receiving any power either. (Is there something I can test or reset with not receiving power? Some circuit or ground that I tripped here? Although it’d have to be a circuit/ground that connects both the battery and charge port too since neither work…)

6) iPod will not respond to being plugged in except for a few things:

—a) my PC does make the normal “USB ding-a-ling” noise anytime I plug the 30 pin connector in to the iPod or disconnect it, so the PC recognizes something, even if it’s just a simple circuit completing that signals the dinging on my computer. My PC does not recognize the iPod at all otherwise (so no iTunes or looking through folders on the HD).

—b) while connected, I can hold the Menu/Center button combo to reset and after the usual 5-7 seconds, I get the computer to make the disconnect dinging noise, then it immediately makes the reconnect dinging noise (I’m hoping this is a big clue. I don’t know how the reset mechanism works, or if it’s a mechanical or electrical system, but activating it does seem to disconnect and reconnect the iPod from the power source, indicating there is at least a sliver of response to that one single input).

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My apologies for the lengthy post, but I’m so stumped as to what caused this, I wanted to include every detail and my whole thought process. I’d hate to have to buy a whole different iPod, or move on to a new mp3 altogether. :( Thanks so much for your time!