For screens i suggest Joesge, https://www.joesge.com/products/fitbit-charge-4-fb417-repair-replacement-parts?_pos=2&_sid=79949e2c2&_ss=r for a water resistant seal it would be best if you use a water resistant glue, Make sure you let it set and seal the proper amount of time, My biggest issue with charge 4’s are the plastic bezels. as it makes it more difficult to get the screen off without damaging the bezel. Best of Luck Dave