Before installing a new display, it's very important to remove all traces of the old adhesive from the frame, while taking special care to remove any small glass fragments in case your display was broken.

Remove any remaining adhesive from the phone, and clean the glued areas with isopropyl alcohol (90+%) and a lint-free cloth.

If the frame is bent, or if any glue or glass remnants are left behind, the new display will not mount correctly and may be damaged. If necessary, replace the frame.