The moboplay device will autoselect the output type depending on what is connected when the player is turned on.   If you initially turned on the player while the component cable was connected; to switch to HDMI, simply plug in the HDMI cable, and then power cycle the media player by unplugging it and plugging it back in.  This should enable the HDMI output.

Vice versa if you are trying to use HDMI after initially turning on the device using the Component cable.