Default Can't unlock boot loader or flash stock

Hi there,
Has anyone got a way out of this.....
I have a rooted C1905 that I have been playing around with. I want to try CM11 but boot loader unlock fails with a "FAILED (unknown status code)" report after I send my unlock code. I then thought I'd flash back to stock using S.U.S. but that fails too saying that I have a customized rom... which I don't!!! I seem to be stuck! is there anyway to force a stock flash?

Cheers