Fix an iPhone XS with no service

• Following a drop and subsequent system upgrade, the device lost cellular connectivity and failed to register on the network. Begin by carefully examining the motherboard's physical condition. The motherboard must be free from any visible deformation or signs of water exposure.
• Subsequently, the motherboard should be reinstalled within the phone for diagnostic testing. Reconnect the display assembly and battery pack. Ensure the SIM card is properly inserted. If the device powers on, but the ICCID is absent from the display, this suggests a failure to recognize the SIM card.

• Establish a connection between the mobile device and the host computer, then launch3uTools to examine the device's specifications.3uTools cannot access the data pertaining to the baseband version and the Wi-Fi module.
• Given that the device lacks network connectivity following an impact, a preliminary assessment suggests a potential issue with interlayer solder joints. Proceeding with the disassembly of themotherboard is now required.motherboard onto the Heating Platform and remove the protective foam.
• To facilitate the removal of the logic board following separation, secure a screw into the logic board. Utilize a craft knife to sever the adhesive tape.

• Adjust the Heating Platform's temperature setting to180°Cfor the purpose of warming themotherboard. Once the platform achieves a temperature of180°C, use a pair of tweezers to apply pressure to the signal board. Employ another pair of tweezers to secure a screw, facilitating the removal of the logic board. Subsequently, deactivate the power supply and detach the signal board.
• Thoroughly clean both the logic board and the signal board of any existing thermal grease. Secure the signal board within a holding fixture. Apply a small amount of rosin to theSoldering Ironheated to365°Cand utilize soldering wick to eliminate excess solder from the bonding pad. Repeat this process to remove solder from the logic board.

• Utilize PCB Cleaner to meticulously cleanse both the logic board and the signal board, subsequently removing the securing screw. Ensure thorough cleaning of the signal board using PCB Cleaner.
• Securely fasten the signal board and logic board to the Testing Fixture. Establish a connection between the screen and the motherboard utilizing a Test Extension Cable. Further connect the charging port flex cable and the power cable, then initiate the device's power sequence by linking it to a computer.
• Initiate the application of 3uToolsto access and examine device specifications; this allows for the retrieval of baseband version and Wi-Fi module information, confirming that the presence of pseudo-soldering is the root cause of the missing baseband version.

• Following this, the logic board and signal board must be reconnected; position the signal board upon the Reballing Platform.
• Ensure the Reballing Stencil is correctly placed.
• A metal plate should be inserted to obstruct solder paste migration into the motherboard's recesses.
• Distribute a thin coating of low-temperature solder paste, then eliminate any surplus material utilizing an anti-static wipe; subsequently, remove both the Reballing Stencil and the signal board.

Position the signal board onto the Heating Platform; configure the temperature setting to180°Cand apply heat until visible solder balls appear. Subsequently, deactivate the power supply, allow the signal board to return to ambient temperature, and then apply Paste Flux. Carefully align the logic board with the signal board. Proceed with heating at180 °C.

Following the reconnection of components, secure the motherboard within the device's chassis. The device should now power on; proceed to insert the Subscriber Identity Module (SIM) card. Verification of the SIM card's unique identification number (ICCID) is observed. Because of the device's network restriction and the absence of a carrier-approved SIM card, comprehensive functional assessments are presently not possible.