My IPad has a problem powering up
My IPad keeps fluttering between powering up and going off when plug into power source
iPad, iPadOS 16
Cold start from full power down is a fairly intensive battery load. Repeated failure to start fully (boot looping) is most often caused by a very discharged battery and a low rated charging supply, which can’t provide enough continuous power to restart the device.
Your best hope is probably to connect the most capable (highest rated) USB-C power adapter you have available and leave it to try and charge overnight. If that is not successful then you need to arrange to get it checked by Apple and maybe a battery replacement. https://getsupport.apple.com to arrange inspection.
