To reinstall the screen:

Use tweezers or an opening tool to remove all traces of adhesive from the phone frame. You can use high concentration isopropyl alcohol to help with the cleaning.

If you plan to re-use the screen, be sure to remove all adhesive residue from the screen. Be careful with metal tools to avoid scratching the screen.

Apply pre-cut adhesive or double-sided tape (such as Tesa tape) to re-attach the screen to the frame.

During the boot-up process after reassembly, the screen will go through a calibration sequence. Do not touch the screen during this process, as it could result in improper touch calibration and create touch issues.