When your new Kindle Fire is frozen or perform poorly because you might have misconfigured the device, you could hard reset the device back to the factory setting.
Note: When perform a reset you may lost all data and content on the device, so make sure you have backup your personal data be doing the below steps:
Reset via setting menu
1. Tap on Quick Settings.
2. Next select More.
3. Choose Device.
4. Now select Reset to Factory Defaults.
Now your device should reset it back factory setting.
Reset via hardware key
Ensure your device is fully charge before doing this.
1. Press and hold the Power key for 20 seconds and then release the key. Your device will then switch off.
2. Next press the Power key to turn it back on.