[8.9" Kindle Fire HD Q&A, Help & Troubleshooting] Lamere:
First off download the following files

KFHD_SRTv2.1- 8.1.4

img files

KFFirstAide32

or

KFFirstAide64

Extract KFFirstAide whichever version 32 or 64

Copy the folder to c:\

rename it to just KFFirstAide

add that to your path

;C:\KFFirstAide

Open the folder KFHD_SRTv2.1 then open images folder and copy system.img

paste it into the KFFirstAide folder

then open the two other img files you downloaded and paste them into the KFFirstAide folder as well

you should now have:

system.img

boot.img

recovery.img

All three files in the KFFirstAide folder

now

Open up an Administrative Command Prompt from within the KFFirstAide

go to the c:\ drive hold the shift key and right click on the folder KFFirstAide then select Open a command prompt here.

enter this command at the prompt

fastboot -i 0x1949 getvar product

it should come back with

< waiting for device >

If you are stuck at the red triangle screen

Make sure your device is totally off hold the power button for like 30 seconds until it turns off

next plug in your device with the usb cable

it should boot into fastboot mode

and show something like:

product: Jem-PVT-Prod-04

finished. total time: 0.009s

then type this command

fastboot -i 0x1949 devices

should come back with something like this

7EE400003C002FFF fastboot

then type this command

fastboot -i 0x1949 flash system system.img

should come back with something like

target reported max download size of 1006632960 bytes

sending 'system' (907264 KB)...

OKAY [ 48.857s]

writing 'system'...

OKAY [ 60.331s]

finished. total time: 109.193s

next command

fastboot -i 0x1949 flash boot boot.img

should show something like

target reported max download size of 1006632960 bytes

sending 'boot' (8192 KB)...

OKAY [ 0.449s]

writing 'boot'...

OKAY [ 0.571s]

finished. total time: 1.024s

next command

C:\KFFirstAide>fastboot -i 0x1949 flash recovery recovery.img

should see something like

target reported max download size of 1006632960 bytes

sending 'recovery' (8192 KB)...

OKAY [ 0.449s]

writing 'recovery'...

OKAY [ 0.565s]

finished. total time: 1.020s

these next commands take forever

fastboot -i 0x1949 erase cache

should come back with

erasing 'cache'...

OKAY [ 47.246s]

finished. total time: 47.250s

fastboot -i 0x1949 erase userdata

should come back with

erasing 'userdata'...

OKAY [2149.490s]

finished. total time: 2149.494s

and finally

fastboot reboot -i 0x1949

once it starts rebooting disconnect the USB cable

once you are back up and running you will be at version 8.1.4

to get to current version

you can use KFFirstAide and this time run

c:\KFFirstAide\RunMe.bat

use the option enable OTA updates

you will have to make sure ADB is enabled under security first on your kindle

once you enable OTA updates then unplug the USB

Next :

Charge the battery, and then connect to a Wi-Fi network.

Swipe down from the top of the screen, and then tap Sync.

The software update automatically downloads in the background and installs after the download is complete and the device is asleep.

Your Kindle Fire will restart during the software update. After the restart, the message “Kindle is updating” will appear on the screen and when it's finished you will be at the latest software version.