The other day I was changing pads and bleeding the brakes when I did something that made me a little nervous. I grabbed a hand full of front brake when I didn't release the bleeder screw and I got a 'pop' at the master cylinder. Now when I've got the entire system tightened up and full, I can't get any pressure at the lever. Did mess up the 'cylinder or is there just an over-abundance of air in the lines?