Now this is going to be a wee bit technical, and those who do not have the intestinal fortitude might want to give it a pass. For folks who have decided to root their Kindle Fire, by installing the FireFireFire bootloader and TWRP custom recovery, having to throw in custom software like CyanogenMod 7 or Android 4.0 after that is a snap. The main beef that beginners have is this – installing TWRP and FireFireFire might prove to be too high a height to scale, and your problems are exarcebated when you are running on a Windows-powered computer. In fact, many a brave warrior have already bricked their Kindle Fire after attempting this route, but there is hope just yet in unbricking your Kindle Fire.
Most of the time, the Windows drivers for the Kindle Fire are the culprit here, as they were not properly installed in fastboot mode, so good thing a fix is available, although it might require some trial and error to get the job done. The Kindle Fire Unbrick Utility is a Windows app that will make attempts to help you recover from common issues such as having your Kindle get stuck at the FireFireFire boot logo, or when you boot into TWRP but are unable to end up with Android after you reboot. Just download the Kindle Fire Utility before you get started, double-click the KindleUnbrick.bat file after that and follow the on-screen instructions. Any luck with that?