Is there an option in your bios setup to select the discrete graphics? Try selecting that. vgaswitcheroo only supports hybrid GPUs with display MUXes. Some new laptops are MUX-less whihc means the display hardware is only attached to one of the GPUs and the other one is strictly used for rendering. Unfortunately, the X server needs a lot of work to support that scenario so it work be supported any time soon in the open source drivers.