Five button locks
Recently had one go intermittent and then completely fail. But we noticed a pattern... it would only fail when we were wet and cold. So we grabbed a blowtorch, a hammer, threw on some overalls and went to work "gently" heating the lock and providing percussive encouragement. Security patrol walked right by us, totally ignoring two men in somewhat battered clothing working on a lock with blowtorch and dead blow hammer. 2 min and we were in.