breaks

Which brake line are you referring to, the rubber flex hose or the steel line? The most common cause of a failure to release is a constricted rubber flex hose. The next would be the brake fluid is contaminated with a petroleum product. When the brake locks up again, loosen the steel line at the master cylinder. If the brake releases suspect the brake fluid. If it doesn't, open the caliper's bleeder screw. If it releases there, suspect the rubber hose.