iPad Air won't charge

I bought an iPad air broken off of Swappa. The owner said it wouldn't charge. Once I received it I opened it up and soldered in a new charge port. That didn't work. Any idea what else the issue could be? I put in a new battery and it powers up just fine and works flawlessly. When I plug it into a computer, it doesn't recognize it.

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most likely Tristar chip is bad. Possible bad solder joint on the port, so double check that

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