求分析联想A66T刷机提示Sendpreanble can not get ACK 的原因？？

突Eing/li

求救：
刷机提示
Sendpreanble can not get ACK  的原因？？

[15:16:47:734] - Target Debug Message : \"Getting type of Device\"
[15:16:47:734] - Target Debug Message : \"Open an BootLoader Device\"
[15:16:47:734] - Target Debug Message : \"Get type of device successfully \"
[15:16:47:750] - Device ID: 1, Target Debug Message : \"DownLoading file: D:\Software_Downloader_3.9.1.4\Temp\FBF_Ntimheader.bin\"
[15:16:47:765] - Device ID: 1, Target Debug Message : \"Download data finished\"
[15:16:47:765] - Device ID: 1, Target Debug Message : \"Completed DownLoad file: D:\Software_Downloader_3.9.1.4\Temp\FBF_Ntimheader.bin\"
[15:16:47:781] - Device ID: 1, Target Debug Message : \"Getting Version...\"
[15:16:47:796] - Device ID: 1, Target Debug Message : \"DownLoading file: D:\Software_Downloader_3.9.1.4\Temp\FBF_h.bin\"
[15:17:29:812] - Device ID: 1, Target Debug Message : \"SendPreamble can not get ACK\"
[15:18:11:812] - Device ID: 1, Target Debug Message : \"SendPreamble can not get ACK\"

Jy_Kawaii

什么什么啊????????????????????