Posted by Jayce Ooi as Software
Amazon Kindle Fire has silent over-the-air (OTA) software update feature. Therefore, you don’t need to upgrade Kindle Fire manually by yourself. Just turn on Wi-Fi connection and Amazon will push software update to your Kindle Fire when there is new software update available. However, you can also download Kindle Fire Software Update and upgrade it manually.
Kindle Fire Software Update
For me, I download Kindle Fire Software Update for another purpose ~ restores to stock Kindle Fire from custom Android OS like CM7 and CM9. And it will replace custom bootloader, recovery like TWRP 2.0 with stock one too.
Download Kindle Fire Software Update here.