What is the matter with the anti theft door lock diagonal tongue that can t get in

The question I said is too general, if you don't twist the key and don't bounce back? Or press down the handle and don't bounce back, or even the locked state doesn't rebound (this situation doesn't need to be judged, generally only destructively open and replace the whole lock), answer you in the first two cases. If the twist key does not rebound, you can remove the lock cylinder first.

Test the lock cylinder directly, see if the lock cylinder twists smoothly, drives the fork fluently, if so, then it is the lock body problem, if not, the lock cylinder problem; The second problem, the lower pressure handle does not rebound, the same need to disassemble the lock cylinder, to see if the panel and the lock body connected to the square steel is in normal use, if normal then see whether the handle is pressed down normally, if it is normal, then the lock body failure, if not normal, it is the panel handle failure (generally these two parts are one).