There are various reasons for the Kindle frozen on the lock screen. It is common for Kindle devices to become stuck on the lock screen because the operating system performs multi-threaded operations simultaneously. Users can easily fix it when they know it causes of the error. It is also crucial for users to check their reasons so they can quickly fix them. Most of the time, these are the reasons for the frozen screen of the Kindle.

https://ebookhelpline.com/kindle-paperwhite-screen-frozen/

If your Kindle is frozen on the lock screen, there are a few things you can try to fix the issue:

Perform a soft reset: Press and hold the power button for 40 seconds or until the screen turns off. Release the power button and then press it again to turn on the device.

Charge the Kindle: Connect your Kindle to a power source using the USB cable and wait for it to charge. Once the battery is charged, try to turn on the device.

Check for software updates: Go to the "Settings" menu on your Kindle, select "Device Options," and then choose "Software Updates." If there is an available update, download and install it.

Remove the case: If you have a case on your Kindle, remove it and try to turn on the device again.

Greetings,
Peter