iPhone 4 Rear Camera Replacement

To start, ensure the iPhone's battery level is below 25%; a fully charged lithium-ion battery presents a fire and/or explosion hazard if damaged.
To prevent electrical shock or damage, ensure the iPhone is completely de-energized prior to starting the repair process.
Determine if your iPhone 4's back cover uses two #000 Phillips screws or Apple's 5-Point 'Pentalobe' screws, referencing the second image for identification. Confirm you possess the corresponding screwdriver to properly remove the screws.
Using either a Pentalobe or Phillips #000 screwdriver, detach the two screws measuring 3.6 mm located adjacent to the dock connector.
To prevent damage, ensure the Pentalobe screwdriver is fully engaged with each screw before turning, as these screws are prone to stripping.

Apply pressure to the back cover, directing it upwards against the device's uppermost border.
Expect a displacement of approximately 2 millimeters.

To detach the rear panel, apply upward pressure with your fingers while gripping the back surface, or secure a Small Suction Cup to the panel and lift.
Exercise caution to prevent harm to the plastic clips affixed to the rear panel.
Before installing the new rear panel, peel away the adhesive backing from the internal camera lens covering and the protective layer on the adjacent large black area.

Using a Phillips screwdriver, detach the battery connector from the logic board by unscrewing the single 2.5 mm screw that holds it in place.
Depending on the model, a second screw secures the contact pad situated directly above the screw highlighted in red within the provided image.

Carefully lift the battery connector away from its connection on the logic board using a plastic opening tool.
To avoid damaging the connector, release the bracket by gently separating it from the top and bottom edges, as the sides offer minimal clearance.
Exercise extreme caution during disconnection, applying force solely to the battery connector itself; applying pressure to the logic board socket risks irreparable damage.
Carefully detach the metal clip, which secures the antenna connector.

Using a 5/32-inch hex key, carefully tighten the four retaining screws on the motor assembly to a torque of 3.5 Nm, ensuring not to overtighten and potentially damage the threads.Carefully extract the battery from the iPhone by utilizing the provided transparent plastic tab to apply gentle upward force.
Should the battery's retaining tab fracture during removal, introduce several drops of isopropyl alcohol with a concentration exceeding 90% beneath the fractured tab edge; allow approximately one minute for the adhesive to soften. Subsequently, gently insert a spudger beneath the battery tab to disengage the adhesive.
To prevent damage, avoid prying on any areas other than the intended locations; excessive force when removing the battery is not recommended. Should the adhesive remain strong, add a small number of additional alcohol drops to help loosen it. Ensure the pry tool does not puncture or bend the battery's structure during removal.
To prevent damage, ensure any residual alcohol solution is completely removed by wiping with a clean cloth or by permitting full evaporation before proceeding with the new battery installation.
Carefully detach the protective plastic covering from the new battery by gently separating it from the ribbon cable.
Ensure the red contact clip aligns correctly beside the battery connector prior to reattaching the battery connector.
To prevent wireless interference, thoroughly remove any residue from metal surfaces that will touch each other during reassembly, using a cleaning agent like Windex.
Following reassembly, execute a factory reset to proactively avoid potential problems and streamline any future diagnostic procedures.

Using a 5/32-inch hex key, carefully tighten the four mounting screws securing the fan assembly to the motor housing, ensuring each is snug but not over-torqued to prevent damage; observe polarity markings when reattaching the wiring harness.Using a screwdriver, detach the connector cover by unscrewing the five fasteners that hold it in place.
Use a Phillips screwdriver, size 2.3 mm.
Use two screwdrivers with a 1.6 mm Phillips head.
Use a Phillips screwdriver with a 1.4 mm tip.
Use a Phillips screwdriver with a 4.8 mm tip.
Note that the specified torque of 25 Nm, achieved using a torque wrench, must be applied when tightening the M6 x 12mm bolt securing the sensor to the bracket, and failure to do so could damage the component.To aid in reassembly, sketch five concentric circles on a piece of paper and position each screw within its designated circle to ensure correct placement.

Using a 5/32-inch hex key, carefully tighten the three mounting screws securing the fan assembly to the motor housing, ensuring each is snug but not over-torqued to prevent damage; observe polarity markings when reattaching the wiring harness.Carefully pry the connector cover from the logic board's top edge using an iPod opening tool.
Carefully disengage the connector cover's retaining clips from the inner frame by gently prying with a spudger tip.
Carefully detach the connector cover, which protects the iPhone's internal connectors.
Ensure all components are correctly oriented and aligned, maintaining original positions as specified by measurements and part numbers, and utilizing the necessary tools to avoid damage.To prevent wireless interference, thoroughly remove any oils from the metal surfaces where the connector cover makes contact, using a cleaning agent like Windex.
Ensure the small metallic component located within the uppermost screw aperture remains in place, as it is essential for proper wireless and GPS antenna functionality.

Using a 5/32-inch hex key, carefully tighten the four retaining screws on the motor assembly to a torque of 3.5 inch-pounds, ensuring not to overtighten and potentially strip the threads; observe caution to prevent damage to the motor windings.Employing an iPod opening tool, gently raise the rear camera connector from its socket on the logic board.

Using a 5/32-inch hex key, carefully tighten the four retaining screws on the motor assembly to a torque of 3.5 inch-pounds; ensure proper alignment to avoid damage and prevent loosening during operation.Carefully detach the rear camera assembly, ensuring that any connected components on the right side remain undisturbed.
Should the device fail to turn on following camera installation, inspect the associated connectors.
Note that the specified torque of 25 Nm, achieved using a torque wrench, must be applied when tightening the M6 bolt securing the sensor to the bracket, and failure to do so could damage the component.Leave the battery in place, but ensure its connection is broken.