If the sticky key issue has not been fixed search here on the forums and Youtube for instructions and videos for any work to be done . I would inspect the brakes, change hoses ( optional) , bleed wheel cylinders & completely replace all the brake fluid. Stop Tech Braided Stainless brake hose available at Amazon : part # front 950.35001 rear 950.35500
also replace new RCM module ( very easy to replace ) and crankshaft sensor as preventive maintenance both available here , stick with Bosch part for crankshaft sensor : https://www.autohausaz.com/pn/MB-1705450305