If you add a comma: A does not work, as B did. B worked, and A does not work. Without a comma: A does not work as B did=A does not work in the same way as B did. A and B both work, but the way A works is different from the way B worked. By using past tense for B, you imply that B worked well when it was active, but for some reason it is not working now. If you change "did" to "does", the logic becomes much simpler.