here's what the screen in an Iphone setting looks like in BIMx and Google Cardboard.
Does it look any different in an Android phone?
Also, the controls? the only real control with the GoogleCardboard box is that button the right side.
press the button once, an icon of a "walking man" (on left) shows up with and icon of a "book" on right.
move your head around so the little blue hollow circle touches the man...then press the button once again.
you begin walking.