I took my rear brake lever off and once putting it back on it doesnt work well at all. It feels like the brake lever travels until it hits the end of its travel then hits a wall. I tried draining the brake fluid and even turned the rear caliper upside down (as recommended) to get all the air out of the system, however i cant seem to get pressure into it from using the brake pedal at all. Is there an easy way to check if my Rear brake master cylinder is busted? Or anything else i should look at?