Hello,
The screen flashing is likely caused by the ribbon cable not being properly seated.
https://youtu.be/2FxhY7LK3tI
This video shows how to fully replace the screen, you're just looking for the ribbon cable shown at roughly the 1:34 mark, once that's fully seated, your screen flicker should be resolved and you'll be able to repair the hinge in any way you see fit!
If that doesn't do the trick let me know and we'll keep trouble shooting!
Coco,