w850 cannot switch on

[senter]

I've a pair of w850, white and black..
there's no problem with the white one when i want to connect it by XS++..
but when I connect the black one, here's the result..
can anybody tell me what's going on with this phone? and what should i do?



21:26:46| Error: Cannot open phone communication port

......

Install SEUS and SEMC USB flash driver will be installed automatically!