ipad mini 2 wont charge

As described, your iPad battery may have reached the end of its usable life. If the battery has failed, the iPad will not successfully boot to a running state - even when connected to its Power Adapter:

iPad Repair & Service - Apple Support

Your iPad has an encrypted filesystem. Unless the iPad can boot to a running state - and the Passcode successfully entered to unlock the iPad - no data can be retrieved from the device. While data locally stored on the iPad may be beyond reach, as long as you have an iCloud or iTunes backup of your data, the backup can restored to your own device after repair, or to a replacement iPad. If your Photos are synchronised with iCloud Photos, these are already accessible from any computer with a web browser:

https://icloud.apple.com

These support pages should help with troubleshooting battery and charging issues:

Charge and monitor the iPad battery - Apple Support

If your iPad won't charge – Apple Support

Troubleshooting generally requires substitution of the Power Adapter and cable for another known-good item. Most models of iPad require a Power Adapter rated at 12W or greater to reliably charge. 5W Power Adapters intended for older models of iPhone are inadequate to charge an iPad; if the iPad charges at all, charging will be very slow.

Be aware that many computer USB ports cannot source sufficient power to charge an iPad. Unless explicitly designed for charging connected devices, computer USB ports are typically limited to 0.5-1A @5V (i.e., 2.5-5.0W).

If you continue to experience difficulties when using an appropriate Power Adapter of 12W or greater, you might be best advised to seek assistance directly from from Apple Support. You can contact the Support Team using the Support link at top-right or bottom-left of this page. Alternatively, if you have access to another Apple device, you can initiate and manage your support cases using the excellent Apple Support App. If not already installed on your iPad, the App can be downloaded from the App Store:

https://apps.apple.com/app/apple-support/id1130498044

You might also visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to test and assess your iPad, Power Adapter and cable(s):

Genius Bar Reservation and Apple Support Options - Apple

Correct.

As already outlined, unless the iPad can reach a running state - and the Passcode successfully entered - no data can be recovered from the iPad.

Your Passcode unlocks the iPad’s Secure Enclave - this being the secure storage area within which the only copy of the encryption keys, required to decrypt your data, is stored.