During the New Year, my iPhone 12 dropped and caused some malfunctions, barely usable. But a while ago, the battery also swelled and could easily shut down automatically, and it has become completely unusable. After switching to a backup device, I left it aside for a while.
Recently, I remembered it because it can still boot normally, and major functions can still be used normally, so I speculated that there should still be partial failures instead of complete damage. It seemed a pity to scrap it entirely, and I could only resort to using a stainless steel bowl.
I took it apart myself to analyze the failure reason and tried to buy parts to fix it. This article documents the disassembly and resolution process.
Failure Analysis
Manifestation
| Appearance | Hardware | Function |
|---|---|---|
| Cracked back panel Bent frame |
Mute button failure Volume button failure Swollen battery Small liquid leak on screen edge |
WIFI hotspot cannot be turned on Wireless charging failure No magnetic attraction |
Reasons
| Failure | Reason | Solution |
|---|---|---|
| Cracked back panel Bent frame |
Drop impact | Replace with a new back assembly |
| Mute, Volume button failure | Volume, mute button ribbon cable broken | Power and volume, mute buttons are part of the same ribbon cable, the entire power ribbon needs to be replaced |
| Wireless charging failure | Wireless charging coil broken | Needs to be replaced together with the power ribbon |
| No magnetic attraction | Permanent magnets around the wireless charging coil have all fallen off | Some back assemblies come with magnets, and the wireless charging module purchased will include magnets |
| Swollen battery | Damage from drop and squeeze | Need to buy a new battery |
| Small liquid leak on screen edge | Damage from drop | Liquid leakage repair can only replace the screen assembly, |
Purchased parts:
| Wireless charging and power ribbon | Wifi antenna | Feimao 3320mAh battery | Back assembly (seller’s image) | Rui Ju LCD screen |
|---|---|---|---|---|
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 |
 |
 |
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Costs:
- Disassembly back assembly: 67.86 yuan
- Feimao 3320mAh battery: 139 yuan
- Wireless charging module + power volume key ribbon: 21 yuan
- Wifi antenna module: 12 yuan
- Rui Ju LCD screen: 126 yuan
Total: 365.86 yuan
Since the back assembly needs to be replaced, I need to remove all parts from the old back assembly and reinstall them into the new back assembly.
Note: Apple phones use many special specifications of screws internally, so it is recommended to use a suitable screwdriver set. I used IKEA’s screwdriver set, which is of decent quality.
Suggestion: Since there are many internal components and screws, if you take them all apart and pile them together, it will be hard to restore. My advice is to use sticky notes to fold some bags to store each screw and component from the following steps. This way, when reinstalling, you won’t lose corresponding screws and can restore them in reverse order of disassembly.
Disassembly
Screen
- Unscrew 2 screws on both sides of the charging port at the bottom
- Use a hairdryer to heat around the screen, use a suction cup to pry open the gap, insert a pick, gently slide around, and lift the screen from the right side (the left side has a ribbon cable for iP12)
- Remove the shielding cover of the screen ribbon cable (2 screws)
- Remove the shielding cover of the earphone ribbon cable (4 screws)
- Disconnect the battery ribbon
- Disconnect the screen and earphone ribbons (three)
- The screen can be completely separated from the body
Motherboard, Face ID
- Remove the camera shielding cover (4 triangle screws, **1 cross screw**)
- SIM card reader shielding cover (2 screws)
- Disconnect all ribbon cables from the motherboard (11), some ribbon cable sockets are hidden under another ribbon cable, so be careful
- Unscrew 4 screws that position the motherboard
- Lift the black adhesive on the motherboard and gently lift the volume and power ribbon
- Remove the camera (be careful of dust)
- Remove the motherboard
- Gently lift the Face ID ribbon, remove the front camera and Face ID component (be careful of dust)
Lightning Connector
Remove SIM card tray
Unscrew 4 screws, remove the vibration motor ribbon cover
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Remove the SIM card reader
Unscrew 4 screws on the speaker to remove the speaker
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Unscrew 3 screws on the vibration module, disconnect the vibration motor ribbon to remove the vibrator
Unscrew 2 cross screws on the left side of the original vibrator position, and 3 Y screws, then remove the left microphone fixed plate
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Unscrew 4 dual-head screws and 2 Y screws
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Also unscrew the last 2 cross screws
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Use a hairdryer to heat the Lightning connector ribbon
Separate the Lightning connector ribbon (do not pull hard, be careful while separating as it’s glued)
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Use tweezers to lift the left and right microphones off the back cover, separating them (control the force to avoid breaking)
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The entire Lightning connector ribbon can now be removed
At this point, the Lightning connector part has been completely separated, and you can first install the Lightning connector, SIM card slot, vibrator, and other parts into the new back assembly.
Top
The components at the top of the phone are: front camera & Face ID, rear camera, flash, Wifi antenna, Bluetooth antenna.
When removing the motherboard, the rear camera’s shielding cover has already been unscrewed. These components are relatively independent and not stacked like the Lightning connector, making disassembly relatively simple and won’t be elaborated on further.
Others
In addition to these components, there are some other small parts that need to be disassembled:
- Volume, mute, and power buttons (the buttons are made of plastic, be careful during installation, as it’s easy to break the button pillars.)
- The locking clips for the screen must also be removed
- There is a small black plastic pillar on the inner side of the SIM card slot that pops up the card slot when the eject pin is inserted.
Be careful not to miss any removable parts.
Screen
The previous liquid leakage issue has become increasingly severe, showing obvious screen flickering at low brightness. So I purchased a budget domestic LCD screen replacement that supports True Tone for 120 yuan on Taobao, plus 6 yuan shipping.
The effect is okay, reaching about 80% of the original screen’s effect. The touch sampling rate is not high, so it may not be suitable for gaming, but the ordinary usage feels fine.
Moreover, the thickness of the LCD screen is slightly thicker, and due to its luminous characteristics, it can cause heat at the bottom of the screen. After using it for a day, I feel the display effect is acceptable, but the battery life has decreased significantly.
Installation Notes:
- Inform the seller to include True Tone when purchasing; otherwise there will be no True Tone function
- The earphone and proximity sensor components from the original screen need to be removed, ensuring proper alignment with the holes; otherwise the light sensing adjustment will fail
- True Tone can only be activated once the earphone is installed and the Face ID is functional
Results
After disassembling each component according to the above steps and replacing the damaged parts, I installed them into the new back assembly.
Moreover, the new battery has better endurance, leaving only the issue of screen leakage that does not affect usage, so I will not replace the screen assembly for now.
In the end, on this almost scrapped phone, I restored all functions to normal, and it can be used as a backup machine.
The original iPhone 12 has a 2815mAh battery, and the health of the old battery dropped to 77%, which basically died after half a day.
After replacement, it is 3320mAh, which is 505mAh more than the original, and the new battery’s health is better, providing better endurance:
References
- iPhone 12 and 12 Pro Teardown
- Detailed tutorial for replacing the back assembly of Apple’s iPhone 12
Conclusion
When I personally disassembled and reinstalled every screw and component on the phone, I was deeply impressed by the wonders of modern industry and solid materials used in Apple products.
As for the repair itself, it mainly involves changing parts; I believe it doesn’t require much technical skill. Being able to turn screws + patience + care can get it done.
In Shenzhen, buying parts in Huaqiangbei is also very convenient. Although I purchased them on Taobao, they were all shipped from Huaqiangbei. The prices for disassembled components are very cheap; the Wifi antenna, wireless charging module, etc. I purchased were all around ten yuan, while having it repaired externally might be very expensive.
For simple repairs on Apple phones, I think it’s completely fine to do it myself. The real issue is feeling lazy about it or worrying about breaking things; it’s not that difficult.
Now, electronic products are all modularly assembled, making refurbished machines very easy. The issue of replacing old with new and using substandard components is also very common in the second-hand digital market. Therefore, one should be cautious when purchasing second-hand or products from unofficial channels. They may look very new, but the internal components might have been replaced, especially after personally going through the operation, I increasingly feel that second-hand items carry risks.
This repair cost a total of 239.86 yuan and took 4 hours. Compared to the cost of the parts, the labor cost would be higher. Doing it myself was purely for fun; I had never disassembled a phone before, and successfully repaired and made it functional on my first attempt. I feel great!
