From sdk-wiki
Baxter Power Down
To power down Baxter, simply press the power button on the back panel of the robot (it's on Baxter's left side).
In a couple of seconds the Rethink Logo splash-screen animation will show on Baxter's monitor for a about 5 seconds, and the robot will shutdown.
Caution!
- Do not hold in the power button when shutting down! Just press the power button for a second. Holding down the power button can cause hard drive corruption on the next boot.
- Do not unplug the robot while it is in the process of shutting down! This can also cause problems for the next time you boot up.