Xiaomi Mi 4 is the legendary smartphone of 2014, which is still used by many users due to its reliability and the ability to upgrade. However, over time, even the best equipment has to be repaired: change the battery, clean from dust, restore the connectors or replace a broken screen. If you decide to disassemble the Mi 4 yourself, this article will help you do it carefully, avoiding the typical mistakes.
Unlike modern smartphones with glue cases and fragile plumes, the Xiaomi Mi 4 is relatively simple — its back cover is mounted on latches, and the main components are available after removing several screws. However, the procedure requires care: improper handling of plastic clips or flexible plumes can lead to breakage. We will examine each step in detail, specify the necessary tools and warn against common mistakes.
Preparation for disassembly: tools and security measures
Before you start disassembling, make sure you have everything you need, and the lack of the right tools is the main cause of damage to the body or internal parts, and here is the minimum kit you'll need:
- 🔧 Plastic blade (or mediator) - to separate the back cover without scratches.
- ⚒️ The screwdriver. PH00 — for the screws of the body (a regular screwdriver can tear the slats!).
- 🧲 Magnetic substrate or container – so as not to lose small screws and parts.
- 🔍 Lump or magnifying glass - will help to see small latches and contacts.
- 🧴 Isopropyl alcohol (90%+) — cleaning contacts when replacing the battery or plumes.
Also prepare the workplace: the table should be clean, well-lit and without static electricity (ideal is to use an antistatic mat). The screws in the Xiaomi Mi 4 are of different lengths - confusing them when you build, you risk damaging the motherboard!
⚠️ Warning: If you're disassembling a phone with a battery that's dead (below 20%), plug it into charging for 10 to 15 minutes before starting work. A fully discharged battery can cause a short circuit if contacts are accidentally closed.
Removal of the back cover: technique and typical errors
The back cover of the Xiaomi Mi 4 is held on plastic latches around the perimeter. To remove it, start at the bottom edge (from the microUSB connector side), where the gap between the cover and the body is most noticeable. Insert a plastic blade into the gap and carefully guide it along the edge, alternately snapping clips.
Don't put too much effort into it -- if the lid doesn't respond, check if all the latches are disconnected. A common mistake of beginners is to try to tear the lid off by force, which causes the plastic locks to break. On the top of the housing (near the camera), the latches are the most fragile -- it's better to use two blades simultaneously, evenly distributing the pressure.
- 📌 Do not use metal tools – they leave scratches and can close contacts on the board.
- 🔄 Move clockwise, starting from the lower right corner (there is a latch less).
- 🚫 Don’t pull the lid up – it is removed parallel to the body, not perpendicularly.
Once you take the lid off, you'll see the battery, the motherboard and the camera. Notice the black protective film underneath the battery -- it doesn't have to be removed unless you're planning on replacing the battery. It prevents short circuits from accidentally coming into contact with the board.
What to do if the latch breaks?
Battery shutdown: why it's critical
Before touching any internal components, be sure to disconnect the battery. Even if the phone is turned off, there is residual voltage left on the board, which can damage sensitive chips if accidentally circuitd. In the Mi 4, the battery connector is located at the top of the board and closed with a black plume.
To turn off the battery:
- Carefully apply the battery connector with a plastic spatula (not metal!).
- Pull the plume up - it should come out of the connector without effort.
- Secure the plume with tape or put it aside so it doesn't touch the fee.
⚠️ Warning: If you notice a spark or a burning smell after the battery is turned off, stop working immediately! This is a sign of a short circuit on the board.
After the power is turned off, you can start removing the motherboard or other components. Remember: you can only touch the board at the edges - touching the chips can leave fat traces that will eventually oxidize and disable the device.
Battery's off.|All metal jewelry (bracelets, rings) removed)|The working surface is clean and dry|Tools are arranged in order of use-->
Extraction of the motherboard: screws and plumes
The Xiaomi Mi 4 motherboard is attached to the body with nine screws of different lengths, their location and length are shown in the table below - remember or take a picture of the order, so that when you build it, you do not confuse:
| Rotor number. | Location. | Length (mm) | Note |
|---|---|---|---|
| 1–4 | By the toll corners | 3.5 | The longest, attach the charge to the body |
| 5–6 | Next to the charging connector | 2.0 | Short, fixing plumes. |
| 7 | Under the speaker | 2.5 | Medium length, often lost |
| 8–9 | Near the camera. | 1.5 | The shortest, fasten the screen plume. |
After the screws are twisted, the board is held by three plumes:
- 📱 Display plume (wide, at the bottom).
- 🔊 Dynamic plume (thin, right).
- 📷 Camera plume (black, top of the camera).
Disconnect them in turn, starting with the display. Use a plastic blade to gently lift the connector. Don't pull the plumes! - they are soldered to the board and can come off. If the connector does not respond, check if the connector is holding the latch (in Mi 4 it is only on the display plume - it must be lifted up before extraction).
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If the plume does not detach, take a picture of its position and carefully heat the connector with a dryer (temperature not higher than 60 ° C. The heat will soften the glue, and the plume will come out easier.
Replacement of the battery: nuances and the choice of a new battery
The battery in the Xiaomi Mi 4 has a capacity of 3080 mAh (original article: BM43). Over time, its capacity decreases and the phone begins to run out quickly. If the original battery is swelling or does not hold charge, it must be replaced. Here's how to do it correctly:
- Disconnect the battery plume (as described above).
- Tap the battery with a plastic spatula on the side - it is glued to the body with bilateral tape.
- Pull it up carefully without swaying. If the battery fails, warm up the body with a hair dryer (maximum 70°C) for 1-2 minutes.
- Remove the remains of old tape and clean the surface with isopropyl alcohol.
- Install a new battery by pressing it for 10-15 seconds to fix the glue.
When choosing a replacement, pay attention to:
- 🔋 Capacity – do not take batteries over 3200 mAh, they may not fit into the case.
- 🏭 Manufacturers - reliable brands: ZOP Power, CAMELION, Patona.
- 📦 Set – the set must be bilateral scotch and insulation film.
⚠️ Warning: If the new battery does not charge after installation, check the thermistor (a small black sensor on the train) if damaged, it blocks charging.
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After the battery is replaced, perform 3 full charge/discharge cycles (0% to 100%) to calibrate the power controller.
Screen Disassembly: When It’s Necessary and Risks
Replacing the Xiaomi Mi 4 is one of the most difficult procedures. The screen is glued to the body around the perimeter, and its plume runs under the motherboard. If you have broken glass or a sensor is not working, first assess the feasibility of repairing: the cost of the original module (article: LCD-MI4-FULL) can exceed the price of the used phone.
If you are considering a replacement, follow this algorithm:
- Warm up the body with a hairdryer at the edges of the screen (temperature 80-90 ° C) for 3-5 minutes - this will soften the glue.
- Insert a plastic blade into the gap between the screen and the case and carefully guide it along the edge.
- Raise the screen by 1-2 mm and disconnect the plume (it is under a metal cover that needs to be unscrewed).
Main risks:
- 🔥 Overheating – if you hold the hair dryer for too long, you can damage the matrix or plume.
- 💥 The rupture of the plume - it is very thin and easily breaks with careless handling.
- 📉 Sensor sensitivity drops – if dust or moisture gets under the screen.
After installing the new screen, check it before the final build: plug in the plume and temporarily lock the screen with tape, then turn on the phone. If the image is distorted or the sensor does not respond, the problem may be in the plume or motherboard.
Phone Assembly: How to Avoid Mistakes
The Xiaomi Mi 4 should be assembled in reverse order, but with a few key points in mind:
- 🔩 Screw them in the same order as you twisted them, starting with the longest ones.
- 📶 antenna contacts – make sure that the metal “tissues” on the back cover fit tightly to the board (this depends on the quality of communication).
- 🔋 Battery - before connecting the plume, check if there are any damages to it.
Typical errors in assembly:
- 🚫 Twisted screws - can damage the thread in the body.
- 📵 Unconnected plumes – if the camera or speaker doesn’t work after assembly, check their connectors.
- 🔌 Poor battery contact – the phone may not turn on or spontaneously shut down.
After assembly, perform the test:
- Turn on the phone and check the sensor, camera, speakers.
- Connect charging – make sure that charging is underway (the indicator should burn).
- Call the phone and check the microphone and speaker.
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If after assembly the phone warms up stronger than usual, most likely, you forgot to install a heat pad between the processor and the back cover.