Before starting any repair, make sure your Galaxy S4 is completely powered off. Hold the power button and select 'Power Off' from the screen. Wait until the device is fully off.

Using your fingers or a plastic opening tool, gently pry off the back cover. Once removed, carefully take out the battery using the plastic opening tool to lift it from the compartment.

Using the Phillips #00 screwdriver, remove the screws securing the midframe. There are typically 9 screws. Keep these screws safe. Next, use a plastic opening tool to gently pry the midframe away from the rest of the phone.

Use a heat gun or hairdryer to evenly heat the edges of the screen. This softens the adhesive holding the screen in place. Once heated, use a suction cup to gently lift the screen while using a plastic opening tool to separate it from the body. Be cautious not to damage the home button or cables.

With the screen partially detached, carefully disconnect the ribbon cables attached to the screen using tweezers or a spudger. Take note of their positions for reassembly.

Connect the ribbon cables of the new screen to the motherboard, ensuring they are securely attached. Align the screen correctly with the phone's frame.

Apply adhesive strips or double-sided tape around the edges of the frame. Gently press the new screen into place, ensuring it is securely attached without gaps.

Reattach the midframe by aligning it with the phone and securing it with the screws you removed earlier. Reinsert the battery and snap the back cover back into place.

Turn on your Galaxy S4 and test the new screen to ensure it is working properly. Check for touch responsiveness and display clarity.