If the 2016 is the same as the 2015, there is a hole in the fender between the steps and the front tire to give access to manually open/close the slide. There is a geared shaft with a pin through the end of it. The picture below shows the tool that came with mine (in front), but I could not figure out what to do with it. The dealer said that is what FR sent with the Vibe??? I made a tool (back one) from an old deep well 1/2" drive socket (used a cutoff tool to put slots down the sides) and a long extension from Harbor Freight. This way I could use it with a cordless impact driver to open/close the slide if it lost power. The socket can also be used on the stabilizers if they lost power. You would use the socket only on the drivers side end of the stabilizer mechanism.
Somewhere I read that you are supposed to disconnect the power connections to the motors before manually operating them. This is supposed to prevent damage to the motor. I made the tool to take along for insurance, tested its operation but never had to use it because of a failure.