How do I fit my replacement screen into a slightly warped frame?

I'm currently 95% of the way through replacing the screen of my old iPhone 6s. The screen is functional, but I'm running into a slight mismatch between the frame of the case and the screen, possibly due to the frame being slightly out of shape (upper left hand corner is the culprit, from the looks of it). I'm able to lower the screen into the frame, but as I do so, a small gap forms at the top which causes the bottom part of the screen to sit slightly outside the bottom of the frame, preventing it from completely lowering into place. Is there a way that I can (as a novice) shape the frame so that the screen can be placed in correctly / is there a special tool that would help me do so? Thanks for your input!

Edit: pics for reference