send it back, they have a 2 year warranty, mine failed last week, same issue.
just remember if you switch brake brands you may need a matchmaker for the sram shifter.
i hadnt planned to buy another sram brake, but the adaptor seems sold out on a few sites or £30, so easiest option (seen as ardrock is only a few days away) for me was a straight replacement.
i was gutted yesterday when it arrived and the front brake from crc appeared to be a left handed as it was ziptied in the box,
i rang crc and the nice lady said oh those brakes are ambidextrous, just turn it upside down :0)