Individual device controls can be found on the device action menu to the right of the device name on the Lab toolbar.
This menu has he following buttons which only control that particular device:
Power off
Switches off the device by sending a shutdown signal to the device (device progress is lost).
Refresh
Refresh the connection and state of the device
Reboot
Send a reboot signal to the device (device progress saved only whilst in the lab).
Reset
Reset the device (device progress is lost)
Suspend
Sends the device into an effective Standby state (device progress saved only whilst in the lab).