For a while, it looked like Rethink Robotics would shake up the world with its collaborative robots: rather than having to write code, workers could teach bots to perform tasks by guiding them through the process. However, the market doesn't appear to have shared its vision. Rethink has suddenly shut down after a potential buyer backed out of a deal. Sales of Baxter and Sawyer robots weren't meeting expectations, Rethink chief Scott Eckert said, leaving the company low on cash. It really needed this acquisition to go through, in other words.