Iphone 14 pro max suddenly heating up even when turned off
My iPhone 14 pro max begin suddenly to heat up even when it's turned off, battery health is still 100% but I'm unable to charge it above 30% and the battery drain's quickly even when turned off.
Here is simple scenario to better understand the problem,
I charge the battery until it doesn't charge any more but it becomes very hot.
I turn it off (not just the screen but the entire phone)
it keeps heating up until all the battery is drained
Do you have an idea what can cause this and if you have any solution please, I can no longer use my iphone.
Thank you in advance
iPhone 6, iOS 11