My rearview mirror recently came unglued from my windshield. I cleaned off the glass and re-glued the metal button onto the glass yesterday. But when I go to reattach the parts to the button, I can't seem to put enough force on the metal "clip" (?) that holds the mirror bracket to the metal button. It is so hard that I feel like I need to hit it with a hammer to try and force it. But I know that's not right. Can anyone help me?

Thanks!