It has come to my attention that under certain circumstances when the Kindle HD's get stuck in a bootloader bootloop the information on the "boot0" block of the internal storage can be ERASED and RESET.
This partition is special and contains ALL of your device's hardware specific information:
- Wifi MAC address + Encoded Secret for registering w/ Amazon services
- BT MAC address
- Serial #
FOR BACKING UP THIS PARTITION:
adb shell su -c "dd if=/dev/block/mmcblk0boot0 of=/sdcard/boot0block.img" adb pull /sdcard/boot0block.img
FOR RESTORING THIS PARTITION:
(do not do this unless you are absolutely SURE that your boot0 block got wiped out -- hopefully you never need to)
This is done via adb from your PC while the device is in TWRP recovery or in the Android OS (not fastboot):
cd <your safekeeping files> adb push boot0block /sdcard/boot0block.img adb shell "echo 0 > /sys/block/mmcblk0boot0/force_ro; dd if=/sdcard/boot0block.img of=/dev/block/mmcblk0boot0;"