You don't mention how much you have invested in the venture. If the investor is paying for everybody's salary (including yours), then the golden rule applies (he who has the gold, makes the rules).
In the hi-tech space, execution is more valuable (in the long run) than finance. Does your investor understand that? If your ideas are really good, you could stall and find a new investor who has an acceptable view on equity.
Given that Andrew and software team want equity - are they willing to pony up funds? that way you might be able to bootstrap the business. If you are able to bootstrap the business, then I would fire Andrew but not the team.
If I were in your position, I would lock-out everybody. Shutdown the servers, etc to preserve the software. Then hardball negotiate with both Andrew and the investor - separately. At the same time seeking out other potential investors. It might take a couple of weeks, but in terms of the long-term I would see it as a risk worth taking.