This method is working 100% for me - tried 4 times until today:
Follow the explanations strictly and it will be ok.
Download this file to downgrade from B708, then do a local update:
After your phone boots up, do the same with the Unicom 2.0 version.
Once both have been done, you'll be able to install EMUI 2.3.
It will have to be a forced update though, because you'll get many "... process has stopped" errors, or it will give you the VERLIST error when doing a local update. So make a backup before you do this.