[7" Kindle Fire HD Q&A, Help & Troubleshooting] bogie6040:
As I had promised, here is what I did to recover my KFHD 7" 2012 (TATE):

PART 1

Prerequisites:

Hard bricked Kindle (aka black brick - no signs of life)

micro SD card to SD card adapter (will be sacrificed)

USB SD card reader

wire, solder, magnification, 50K ohm resistor, lots of patience...

Remove the main board from your kindle observing ESD precautions. If like me your kindle was shelved for a wile waiting for this "cure" you should make sure your battery has enough power, I had to charge mine with a bench power supply set to 4 - 5V and making sure that the amperage didn't exceed ~2A - you will need some really fine wire to insert into the connector on the battery (red is +4 - 5V and black is GND) Since it will take a while to charge you can set this up and monitor it periodically while performing the rest of this procedure, keep a close eye on it though, you do not want the battery becoming hot to the touch. If you aren't familiar with manually charging a lithium ion battery you should probably skip this part or at least do some research and try it on something else first.

Obtain a micro SD to SD card adapter and carefully cutout the plastic on the top side where the micro SD card would sit and connect some fine wires (I recomend 28 AWG and a different color for each) to the contacts. In addition a 50K ohm resistor needs to be between pins 2 (DAT3) & 4 (Vcc) of the micro SD card adapter contacts - I used a 1206 size 49.9K ohm after the wires were soldered. In retrospect I would use an 805 size resistor before soldering wires, anything betweeen 40K and 60K ohms should work.

View attachment 3544806

View attachment 3544807

Connect the wires to the points on the main board following the pictures above and the following pictures, notice there is a jumper between capacitors C801 and C803 (this was some 30 AWG solid rework wire) You will aslo note the brown wire is disconnected from TP805 (this was done for clarity in the photo for connection points of C803) it needs to be connected for this to work.

View attachment 3544809

View attachment 3544808

Some notes on performing this procedure in general:

You will be performing some fairly fine pitch soldering - I highly recommend a magnifying scope of some kind (9 - 10X)

Pre tin the contacts you will be soldering to and strip and pre tin all the wires you will use prior to starting (this lessens the likely hood of nicking the wires with the hot iron and burning off the insulation - because you wont be switching operations from wire prep to soldering)

I suggest using a DMM (continuity check) between all the solder points you make, first on the SD card adapter (wire it first) and then on the board after all connections are made to make sure you didn't short something out.

This is a static sensitive board and software recovery procedure (since the main board is out of the kindle while hooked up to your computer)

I used a USB A to A extension cable to my SD card reader, make sure you use long enough wires to attach the adapter to the main board - mine were aproximately 7" long...

Patience Patience Patience - if you are not used to doing soldering like this, practice on something else similar and inspect your work both visually and with a DMM.