Begin by completely powering off your Samsung Galaxy S4 Active. Press and hold the power button, then select 'Power off' from the menu. Wait until the device is fully shut down before proceeding.

Use the plastic opening tool to gently pry off the back cover. Once the cover is removed, take out the battery by lifting it from the bottom edge.

Use the Phillips #00 screwdriver to remove all screws securing the midframe. Carefully separate the midframe using a plastic opening tool, ensuring you do not damage any internal components.

Apply gentle heat to the edges of the screen using a heat gun or hair dryer. This softens the adhesive holding the screen in place. Keep the heat source moving to avoid overheating any single area.

Attach a suction cup to the screen and gently pull to create a small gap. Use a plastic spudger to carefully separate the screen from the frame, working around the edges. Be gentle and patient to avoid damaging the display cables.

Once the screen is detached, carefully disconnect the display cables using tweezers. Handle the cables gently to prevent tearing or damage.

Connect the new screen's cables to the motherboard, ensuring they are securely attached. Align the new screen with the frame and press it into place. Use adhesive strips to secure the screen if necessary.

Reattach the midframe by aligning it with the device and securing it with screws. Insert the battery, then snap the back cover into place.

Turn on your Samsung Galaxy S4 Active and test the new screen to ensure it is functioning properly. Check for touch responsiveness and display quality.