移动H2-2超密xml无法解压

redboy3

新装移动宽带，光猫H2-2，telnet已经打开，将cfg.xml配置文件得到。
但Offzip解压出错，显示- zlib Z_DATA_ERROR, the data in the file is not in zip format
  or uses a different windowBits value (-z). Try to use -z -15
求助！