[8.9" Kindle Fire HD Q&A, Help & Troubleshooting] Moor Terces:
First of all, you have to be kind of crazy to try this and it is very risky, but if your here you've already bricked your Kindle so...

Next, you need to get your mother board out of the Kindle. There are teardown instructions if you do a search. Tip: don't pry on the side with the USB connection. That side of the case has bigger tabs that act almost like a hinge. Also it helps to have a specialized plastic pry tool. I got one from radio shack. After opening the case like a book, carefully unhook the ribbon cables and the rest of the teardown is easy.

You then need to make the interface. Use this post and follow the instructions from kurohyou. These instructions are for the KF2 but the methodology is the same. Making the interface will be identical. For connecting the interface to the motherboard, instead of using the images in that post, use the images of the mother board in the OP of this thread. You need to carefully peal the yellow protective coat off of the back of the motherboard to access the small copper pads. Tip: the VCC connection is daunting but if you put a tiny bit of solder on the tip of the wire and heat only the wire it will stick. You don't need much solder for any of these connections. Use a toothpick to put tiny amounts of flux on each connection. Practice on something else to sharpen your skills before attempting on your Kindle. Also labele your wires before you start to reduce the chance of errors.

Personally, I used a micro SD to SD adapter as that is what I had on hand. A big thanks to lex66676 for posting this image. Either way will work.

Next you will need to get Ubuntu up and running. Forget Windows, it will never recognize the chip. You can create a bootable disk or USB and use Ubuntu on your computer without even installing. Go to the Ubuntu website to find instructions and downloads. Tip: I would do this on a computer with a traditional BIOS rather than the newer UEFI as you will probably have less issues. Also, Windows 7 is easier to boot on external media but it is possible on Win 8 by holding shift while clicking reboot to get to the advanced boot options. Once you have Ubuntu running, mess around with it for awhile to get comfortable.

The moment of truth. Connect your interface and see if it recognizes the chip. Open gparted or the disk utility to see if you see the partitions. Note the name of the partitions. Mine was called /dev/mmblk0p2 for partition 2 then the same ending in 9 for partition 9 etc. (The name might have been something a little different, but I'm not going to take it apart again to get the exact name heh heh.) Tip: Gparted might give you an error regarding the table. That's ok do not attempt to fix it. Gparted should still see the partitions. If Ubuntu doesn't see your chip try another computer. The first computer I tried didn't work. If that doesn't work recheck your connections and make sure you have the right wires to the correct terminals.

Now you need to compile your files. Get a working bootloader from Hashcode here step 2 number 6. It is the 8.1.4 bootloader. Also find a Kindle HD 8.9 boot.IMG and recovery.IMG either from your own backup or from the Kindle Fire First Aid package. I navigated to the home directory of Ubuntu and made a folder called Kindle and added the three files. Now you need to open a terminal and navigate to your folder. Use the command "cd /home/Kindle" and it should point your terminal to the folder with the files in it. Tip: The terminal is case sensitive. Also if you are booting from a live CD or USB it can be finicky. I had to use the xterm for it to work as the normal terminal wouldn't change dir. I also could only move one level at a time by using command "cd /home" and then "cd /Kindle".

Once you are in the right directory you are going to use the dd command to write your files. The red portion will be the name you noted from gparted.

Partition 2 with the bootloader:

Code: sudo dd if=kfhd8-u-boot-prod-8.1.4.bin of=/dev/mmblk0p2 bs=1

Partition 9 with recovery:

Code: dd if=recovery.img of=/dev/mmblk0p9

Partition 10 with boot:

Code: dd if=boot.img of=/dev/mmblk0p10

After running each of those commands, again red being the name your computer gave your chip, you should see some info on how fast it took etc as a confirmation. Shut the computer down, eject the interface and carefully remove your wires. Tip: when your wires are removed if you very quickly touch the small amount of solder left on the pads it will make a tiny smooth bead that you can use if you have to resolder again. Take care not to linger with your iron so you do not overheat the board. Also don't do this to the vcc component as it is just too tight of an area.

After removing the wires, use electrical tape or something similar to cover the exposed pads on the back. Make sure not to cover the copper around the screw holes that were originally exposed. Now put it back together. Remember to slide the side with the USB port in first as it acts as a hinge.

Moment of truth 2! Plug it in to charge as the hard brick completely discharges the battery. For me, after a few minutes I was able to see the charge icon pop up. Walk away and wait awhile as this kindle takes forever to get a charge built up. Come back and hopefully you will see that the kindle is on and running, or at least you can see the kindle fire logo. If there is any life to it you can use the other techniques to get it back up.

Last but not least, do not do the same thing you did to brick it in the first place!!!