Systems, methods, and apparatus for testing devices adapted for connection to other devices using universal serial bus (USB) are disclosed. Devices to be tested are caused to enter a special mode of operation when a resistance measured across across two terminals of a USB Type-C connector has a value associated with the special mode of operation. One or more operations of the device are automatically initiated when the resistance between the two terminals has a measured value that matches one of a set of resistance values maintained by the device. The one or more operations may include configuring a power management circuit based on the measured value, and entering a special or factory boot mode that controls startup of at least one processor on the device based on the measured value. Each of the set of resistance values exceeds a minimum open-circuit resistance value specified for the connector.