A dead bolt lock (214) automatically blocks the extended bolt (204) to prevent externally-applied force from thrusting the bolt (204) back into the lock case (100), and in the event of physical attack the lock responds by prolonging or perpetuating the deadbolt blocking condition. A push-pull lock has a bolt whose motion in both directions is stopped in response to detection of a rise in motor current above a certain level: a cushioning arrangement allows the current-limiting feature (600) to be implemented without risk of damage to the motor (202), gear teeth or other drive components. A re-locker arrangement includes an angled flange that is part of a motor-supporting bracket (206); when forcibly pressed, the flange breaks plastic pins (920) to release a spring-biased re-locker wire (950) to block the bolt from being withdrawn. The system also provides a position sensor switch (692), a keypad tampering detection and response system (646), remote enable/disable unit (5), duress detection and response unit (7), low-battery sensing arrangement (600) and bolt extension indication, adjustable bolt throw and audit trail features.