Have you plug the power point into your Kindle Fire but you noticed that the battery just wont charge. You may try to keep the charging overnight but in the morning you still noticed that the power charge keeps dropping. If you experience this then you can try the following:
1. You could try to hard reset the device and see if it fix your problem.
1.1. Press and hold on the Power key for around 20 seconds and then release the button. Your device should then proceed to switch off completely.
You can other detail methods of reset here: Kindle Fire: Hard Reset Back to Factory Setting.
2. Try to use another wall charger or USB charger as Amazon charger maybe faulty.
3. Try to use car charger.
If it's a charger problem you can always requested Amazon to give you a replacement charger, otherwise you may have to bring your device back to the support centre to have them fix it.