my kindle is not jailbroken。
I used 1.8V TTL USB linked RX,TX,GND
Choose the 4 Erase MMC0,
Brush into PW2's（kernel main_kernel.img，diags_kernel diags_kernel.img）by the fastboot。I think that can be general....it's my fault
Firmware Version 5.65（PW3,300ppi）
U-Boot 2009.08-lab126 (Apr 15 2015 - 07:37:55)
CPU: Freescale i.MX6 family TO0.0 at 996 MHz
Temperature: 31 C, calibration data 0x5ae53a5f
mx6sl pll1: 996MHz
mx6sl pll2: 528MHz
mx6sl pll3: 480MHz
mx6sl pll8: 50MHz
ipg clock : 66000000Hz
ipg per clock : 66000000Hz
uart clock : 80000000Hz
cspi clock : 60000000Hz
ahb clock : 132000000Hz
axi clock : 198000000Hz
emi_slow clock: 22000000Hz
ddr clock : 396000000Hz
usdhc1 clock : 198000000Hz
usdhc2 clock : 198000000Hz
usdhc3 clock : 198000000Hz
usdhc4 clock : 198000000Hz
MMC: FSL_ESDHC: 0,FSL_ESDHC: 1,FSL_ESDHC: 2
Board: Muscat WFO
Boot Reason: [ POR ]
Boot Device: NAND
Board Id: **************
S/N: ****************
I2C: ready
DRAM: 512 MB
Using default environment
In: serial
Out: serial
Err: serial
Quick Memory Test 0x80000000, 0x1fff0000
POST done in 111 ms
Battery voltage: 4041 mV
Hit any key to stop autoboot: 0
## Booting kernel from Legacy Image at 80800000 ...
Image Name: Linux-3.0.35-lab126
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 2420416 Bytes = 2.3 MB
Load Address: 80008000
Entry Point: 80008000
Verifying Checksum ... OK
Loading Kernel Image ... OK
OK
Starting kernel ...
[ 0.093625] boot: C def:bcut:batterycut=1
[ 0.250842] max77696-battery max77696-battery.0: MG characterization data not found, check boardid [-22]
[ 0.271818] LPDDR2 MfgId: 0x3 [Elpida]
3.0.35-lab126 #1 Wed Aug 28 15:30:45 PDT 2013 armv7l
[ 0.392663] mmc0: unrecognised EXT_CSD revision 7
[ 0.397387] mmc0: error -22 whilst initialising MMC card
[ 0.611526] mmc0: unrecognised EXT_CSD revision 7
[ 0.616254] mmc0: error -22 whilst initialising MMC card
[ 0.839608] mmc0: unrecognised EXT_CSD revision 7