How to manually charge iPad Air 4 batter

Hello, I bought an iPad air 4 in Jan 2022, in Feb 2023 after an update it stopped charging. I took it to the geniuses and they said, yes it's broken, but you're a few weeks out of warranty so we can't help. But they gave me proof that it breaking was a defect and not my fault. But he did ask if I got the update earlier that week and made a pained face when I said yes, so I always suspected he knew their update bricked my device.

Unfortunately I bought it new sealed off eBay but the seller has been unresponsive on proof of purchase so I can't go to Curry's for a replacement.

I'd like to try removing the battery, manually charging it by connecting it to a power source, and seeing if it will boot. If it does I'd like to update the software and see if it resolves the issue because I've read articles of a few people who got around this issue by enabling developer mode, which allowed them to charge and then the problem resolved with the next update.

But because I cannot charge I cannot update the device. The battery was working perfect before the update so I'd prefer to try charging it first before a replacement.

What I don't know is which are the positive and negative points on the battery and can I connect the usb-c via alligator clips too them or do I need an additional tool to change the power to something that won't damage the batter?

Of course a sanity check on this idea or if there's a better one is welcome. No one will replace it, apple will fix it for a ridiculous price, so right now I just have a bricked iPad so I'm willing to take some risks.