This is a voluntary pop quiz.

You're circling in a 30 degree left bank at 3000 AGL.

You hear a thunk and the glider enters a spin. Your practiced spin recovery technique does not work in the usual amount of time. You look in the direction of the thunk and see that the left spoiler is full open, you confirm that the spoiler control handle is in the fully closed position. A quick look confirms that the right spoiler is full closed.

What do you do next? Why did the left spoiler pop open. What just happened?

To derive the full benefit of this exercise, you might respond to this thread with your answer before looking at any of the other replies.

My hypothetical solution and explanation follows as the next comment.