iPhone 13 Mini Not Charging or Randomly Restarting? Fix It in Minutes

In our daily lives, iPhone 13 Mini owners may run into two annoying problems: the smartphone abruptly shuts off or won't charge. These problems can conceal deeper problems like hardware malfunctions or system irregularities in addition to impairing the user experience. Using a number of real-world repair scenarios, Phonefix will walk you through the process of diagnosing and fixing the "Automatic Restart + Unable to Charge" problem on your iPhone 13 Mini, offering concise and useful advice!

I. Problem Description and Initial Diagnosis
Device Information:
[Model]: iPhone 13 Mini
[Customer Description of Problem Symptoms]:
· The iPhone automatically restarts and cannot enter the system;
· No response after plugging in a charger, with no charging status displayed;
· Testing with multiple chargers and data cables yields no results.
Based on the symptoms, these issues could be caused by software anomalies (system crash, update failure), hardware issues (battery damage, USB charging chip, motherboard short circuit, etc.), or even a combination of both. Therefore, the next step is to conduct a step-by-step troubleshooting and repair according to a professional process.

II. Phase 1: Basic Inspection and Initial Hardware Screening
Step 1: Disassemble the Device and Remove the Motherboard
· Turn off the device, disconnect the power cord, remove the screen, disconnect the battery, and completely remove the motherboard.
· Remove the motherboard from external components and perform a "bare board" inspection.
· Observe the motherboard under a HD trinocular microscope; no obvious signs of burning, corrosion, or chip displacement are observed, indicating an intact appearance.

Step 2: Power on the Motherboard
· Use a power meter to power on the motherboard and observe the current fluctuations.
· The results indicate that the device boots normally and enters the system smoothly.
These steps indicate that the motherboard is operating normally in its bare-board state, and the initial diagnosis is that the issue is caused by an external component.

Step 3: Connect external components one by one to troubleshoot
Connect the iPhone screen, battery, and docking station to the motherboard in order to test whether it still boots normally. During testing, we found the following:
· The device could still access the system after all accessories were connected;
· However, it frequently restarted after the battery was connected;
· The charging function was inoperable, with current drawing almost zero;
· It could charge normally when the device was powered off.
This strongly suggests battery aging or damage, as well as circuit anomalies related to the U2 charging chip.

III. Phase 2: Battery Replacement and Determining the U2 Chip Status
Step 4: Battery Replacement Testing
Replacing the original battery with a new, genuine iPhone 13 Mini battery and conducting the following tests:
· The automatic restart issue resolved after the battery replacement;
· The device could access the system normally;
· However, it still could not charge when powered on;
· After plugging in a charger, the current slowly decreased to near zero;
· It could still charge normally when powered off.
This series of symptoms is typical of a USB charging management chip (i.e., the U2 chip) failing to function properly when the system is powered on.

IV. Phase 3: Logic Board Delamination and Chip-Level Repair
Step 5: Logic Board Delamination
The iPhone 13 Mini's logic board is a two-layer structure, requiring delamination to replace the U2 chip. The procedure is as follows:
1. Use a hot air gun set to approximately 330°C to evenly heat the back of the motherboard.
2. Using a motherboard-specific delamination tool, slowly separate the top and bottom layers.
3. Be careful not to damage the BGA solder joints during separation.
4. After successful separation, place the motherboard layer containing the U2 chip under a HD trinocular microscope.

Step 6: Replace the USB (U2) Chip
After confirming the chip model, remove the U2 chip with a constant-temperature hot air gun and re-solder a new one.
· Clean any residual solder from the original pads before soldering.
· Use flux to improve soldering quality.
· After installing the new chip, re-secure it with hot air.
· Verify under a microscope that the chip is correctly positioned and that the solder joints are full and free of dry solder joints.
After the replacement, a simple functional test revealed that the problem persisted.

V. Phase 4: Circuit Troubleshooting and System Reflashing
Step 7: Multi-Point Circuit Measurement
It is suspected that the U2 chip itself is not damaged, but rather that other related circuits are abnormal. I then used a digital multimeter to perform the following measurements:
· Resistance of each power pin on the USB chip;
· Continuity of the USB data cable (DP/DM) to the docking station;
· Resistance of the USB data cable to the CPU controller;
· After removing the U2 chip, I measured the bottom corner of the solder pad to see if there was a short circuit.
No abnormalities were found at any of the test points. This indicated that there was no obvious hardware fault in the U2 chip's operating environment.

Step 8: Flashing the System to Restore the System
Since there were no hardware faults, it was likely an issue with the system driver layer, preventing the USB module from activating properly during power-on. Therefore, I decided to perform a system recovery:
· Reinstall the motherboard into its housing;
· Connect the computer using a Lightning cable;
· Successfully recognized by the computer, indicating that the USB function was still functional;
· Perform a complete flash using Aisi Assistant or iTunes;
· The flashing process was successfully completed, and the system was successfully reinstalled;
· Powering on the computer for testing, I found that charging was back to normal, completely resolving the issue!

VI. Repair Results and Functional Testing
After the flashing process was complete and the device was reassembled, the final functional testing phase began:
· Automatic restarts completely eliminated;
· Charging functioned normally both when powered on and off;
· Charging current remained stable;
· WiFi, Bluetooth, camera, fingerprint sensor, earpiece, microphone, speaker, and incoming calls were all tested and all functioned normally;
· Final customer acceptance was obtained.
The repair was successfully completed!

VII. Daily Maintenance Recommendations
· Avoid using non-original chargers during daily use;
· Regularly check system status and perform timely updates;
· If you encounter restart or charging issues, first try a force restart or factory reset;
· If the problem persists, contact a professional repair technician as soon as possible to prevent further problems.

The principle that system problems are frequently strongly tied to hardware problems has been demonstrated once more by this thorough repair procedure. Precise operation and scientific judgment are more beneficial than mindlessly replacing parts. Please follow China Phonefix News for regular updates on professional repair information if you're also looking for professional repair guides. Phonefix trust this post will be a useful resource.