Why does my iPad keep flashing
iPhone 7 Plus, iOS 15
Question marked as
Given the age of your iPad, it is very likely that its battery has reached the end of its usable lifespan - and has failed. All rechargeable batteries have a finite service life - and must eventually be replaced.
That said, your iPad is obsolete. Official Apple Service Providers will not have parts available with which to offer a battery replacement. You might try finding an independent repairer, but doing so is unlikely to be cost effective.
In replacing the iPad battery, all data and installed Apps will be erased. It will not be possible to reinstall Apps from the Apple App Store - as compatible App for your iPad have been long since removed from the App Store.
Realistically, your only real option is to consider replacement of the iPad with a much newer model that is supported by Apple.