Unused ipad mini A1455 for 5 years

Hi, i misplaced my ipad mini and just found it after 5 years (since September 2015). I have charge it over 2 days, unresponsive, not even a little heat. So i decided to DIY and replace to a new battery. Now its a little hot, a sign that the ipad is charging? but it’s still black screen. i tried holding both home button + power button for 20 seconds but no luck. Im using the original charger which came along with my iPad 7th gen. any idea how to fix this? i need the data inside. I even connected to my PC but nothing happened.