BANG ONE'S HEAD AGAINST A BRICK WALL
bang one's head against a brick wall: translation
beat one's head against the wall & bang one's head against a brick wall
Fig. to waste one's time trying hard to accomplish something that is completely hopeless. •
You're wasting your time trying to figure this puzzle out. You're just beating your head against the wall.
•
You're banging your head against a brick wall trying to get that dog to behave properly.