@benjaminanaman your phone has an AMOLED. Display. When these crack they leak. The only way to repair this is by replacing the screen.
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Since iFixit does not yet have a guide for this, use something like [https://www.youtube.com/watch?v=YHXeLsvwzSM |this video] to replace the display. Replacement displays are available at many online stores.
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While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.