Intermittent front brakes lock up

Single owner car purchased new! This car has been no trouble until now. Six months ago front brakes locked up while driving. Car had been in garage all weekend. Got back from a trip (another vehicle) and drove approximately two miles city driving when it first occurred. Front brakes locked and hot. Sat overnight before I could arrange a tow. Dealer stumped. No ABS or other lights except a few months earlier the message "Check Stability" displays on the dash. Dealer ends up replacing with a re-manufactured steering gear kit. To quote "steering gear leaking fluid causing brake booster kicking back. Also found steering fluid low and and steering gear and brake booster leaking. Brake pedal kicking back. Also steering position sensor failing intermittently. So, steering gear kit installed. Upon pick up, front brakes locked not two miles from dealership. Next, hydro booster replaced and tested. Vehicle fine for six months and one long road trip. Now, problem has returned. In between dealer repair to present was concerned with front rotor or pad damage. Had replaced front pad with high cost ceramic at Midas with lifetime warranty. Took to Midas for a full inspection. No apparent issues could stand front pad replacement and rear pad replacement. Up shot, no rusted calipers, or other glaring issues. My two cents: take care to a local quick lube each time. Once, brake fluid was low and "topped off" by quick lube person. Could brake fluid have been used by mistake? Would something that simple be the root cause. By the way, no ABS or any other indicator light except "check stability" which I assume is the steering position sensor referenced in mechanic notes. PS. Tried to sell it with disclosure. Drove around block a couple of times with no problem. Seems to bleed off or something. Buyer did not make it two miles before lockup. Could not honorably consummate the deal. Not that kind of guy. Any help appreciated.