台电p78，在官网下的固件程序，P78双核(G1M5)-Android4.1.1-V1.04-5931，按照里边的升级教程操作，到79%的时候就卡住了，是怎么回事啊？
current pc version is: win7
current tool version is: v1.6.9
-----importUpgradeFile-----filenameE:\P78(G1M5).zip
[T 1][06:57:01]: load spl ...
[T 1][06:57:02]: load uboot ...
[T 1][06:57:03]: test command exec: crc 0x8f800000 537540 4d6be4c3
[T 1][06:57:06]: command exec:set_chgcur 0
[T 1][06:57:07]: command exec:video dev bl_off
[T 1][06:57:09]: command exec:video dev disable
[T 1][06:57:10]: command exec:sf probe 2
[T 1][06:57:11]: command exec:sf erase 1000
[T 1][06:57:14]: command exec:nand rom_protect off
[T 1][06:57:16]: command exec:nand erase 0
[T 1][06:57:41]: command exec:nand info
[T 1][06:58:01]: command exec:defenv
[T 1][06:58:02]: command exec:setenv bootargs ${bootargs} a9_clk_max=600000000
[T 1][06:58:03]: command exec:setenv recovery_command --usb_burning
[T 1][06:58:04]: command exec:save
[T 1][06:58:06]: load uimage ...
[T 1][06:58:07]: Transfer Complete! total size is 4034560 Bytes
[T 1][06:58:13]: test command exec: crc 0x82000000 4034560 883c1693
[T 1][06:58:13]: command exec: crc 0x82000000 4034560 883c1693
[T 1][06:58:13]: sendCommandWithReply: crc 0x82000000 4034560 883c1693 maxCount:30
[T 1][06:58:14]: command exec:bootm 0x82000000
[T 1][06:58:18]: boot uImage ...
[T 1][06:58:54]: cannot find disk! 30times
[T 1][06:58:55]: failed because no connected device ,current step is 19