iPod Touch 6G rapid boot loop, dies immediately if taken off charger

This needs a detailed back story beyond just "rapid bootloop, dies if taken off charger"

This was a working iPod Touch 6th Gen, 32GB Gold in a noticeably bent housing. I got a replacement used housing, moved the working board and screen into the used housing, new battery, all worked great until I opened the camera app, which seemingly killed the board, now it does the rapid bootloop and can't hold a charge at all. It never fully boots up, just goes white apple screen to black screen repeatedly.

I don't think anyone would expect a used original rear camera to be dangerous, yes I did already try swapping another rear camera and another new battery, no change.

So I take it I need another logic board? I'd just like to know why iPod Touches die like this. Did the NAND flash die? Charging circuit? Sad this probably can't be fixed.

I got a third battery to test with and it actually worked, the iPod touch lives again!! Seems gotta get a really good battery and make sure it's soldered really well.