OTA升级log保存在/cache目录last_log文件中，打开后拖到最后可以看到出错信息，如：

open emmc partition "boot"
contents of partition "boot" didn't match EMMC:boot:4659200:de057597c4c12a640f8a625ba4edd419bd417377:4659200:9022a2b55d5fdebe5533fca802825627d95f5851
file "EMMC:boot:4659200:de057597c4c12a640f8a625ba4edd419bd417377:4659200:9022a2b55d5fdebe5533fca802825627d95f5851" doesn't have any of expected sha1 sums; checking cache
failed to stat "/cache/saved.file": No such file or directory
failed to load cache file
script aborted: assert failed: apply_patch_check("EMMC:boot:4659200:de057597c4c12a640f8a625ba4edd419bd417377:4659200:9022a2b55d5fdebe5533fca802825627d95f5851")
assert failed: apply_patch_check("EMMC:boot:4659200:de057597c4c12a640f8a625ba4edd419bd417377:4659200:9022a2b55d5fdebe5533fca802825627d95f5851")
E:Error in /cache/update.zip
(Status 7)
Update.zip is not correct
Installation aborted.

以上信息表示bootimg升级失败，但具体原因不清楚，可以暂时关掉bootimg升级来解决，可以做如下修改：

updating_boot = (source_boot.data != target_boot.data)
updating_boot = False


updating_recovery = (source_recovery.data != target_recovery.data)
updating_recovery = False