用缝衣针连接TTL，上电跑码都没问题，到了烧写那一步就出错，实在是没辙了，请大佬教我
附上刷机报错日志：
串口已经连接，请给单板上电，若已经上电，请断电后重新上电。
Timeout error.
Bootrom start
Boot from eMMC
Starting fastboot ...
System startup
Reg Version: v1.1.0
Reg Time: 2014/10/14 10:09:24
Reg Name: hi3798mdmo1d_hi3798mv100_ddr3_2gbyte_8bitx4_4layers_emmc.reg
Fastboot 3.3.0 (sunhuasheng@server180) (Feb 13 2015 - 09:39:43)
Fastboot: Version 3.3.0
Build Date: Feb 13 2015, 09:39:57
CPU: Hi3798Mv100
Boot Media: eMMC
DDR Size: 1GB
Check nand flash controller v610. found
Special NAND id table Version 1.36
Nand ID: 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
No NAND device found!!!
MMC/SD controller initialization.
MMC/SD Card:
MID: 0x11
Read Block: 512 Bytes
Write Block: 512 Bytes
Chip Size: 3776M Bytes (High Capacity)
Name: "004GE"
Chip Type: MMC
Version: 4.0
Speed: 25000000Hz
Bus Width: 8bit
Boot Addr: 0 Bytes
*** Warning - bad CRC or eMMC, using default environment
Boot Env on eMMC
Env Offset: 0x00100000
Env Size: 0x00010000
Env Range: 0x00010000
SDK Version: HiSTBAndroidV600R001C00SPC053_v2014101420
