Samsung iPad lock symbol

Most likely going to need to do a factory reset (which will wipe all data) if the correct passcode doesn’t unlock the boot encryption.

That can be done by booting the tablet into recovery mode by doing the following:

1. Hold power + volume down + home until the screen goes off.
2. Immediately switch to holding power + volume up + home, release power but hold other two keys once something is displayed on the screen.
3. Release the other two keys once you see the recovery mode (usually a light blue screen)
4. Wait for recovery to finish loading up. Menu will show up after a few moments.
5. Use volume up and down to navigate menu
6. Use power button to select highlighted option.
7. Choose wipe data / factory reset. You will most likely need the google account login that was previously used on the device after performing a factory reset in recovery mode.
8. Reboot tablet, this will take a while (5-10 minutes).
9. Once finished booting to welcome screen go through setup and follow the prompts.