I think it is almost too late... :(
How a startup even got into an incubator if they have not done some marketing? As soon as founders came up with an idea for a startup - they must go out and validate it on the market. Are they addressing any real needs on the market? Will they be able to do a right "job" for their intended end users? The answers could be changing through the process but they need to be asked constantly.

An incubator or accelerator is a perfect entity to complement startups lack of resources and bandwidth. They need to whip startups into getting out and provide mentoring and advisement on how to do it right and who to talk to.