Step-by-step dismantling of Xiaomi Mi 4: tools, procedure and advice of professionals

The Xiaomi Mi 4, launched in 2014, is still popular with users due to its robust design and upgrade capability, but over time, even the best-performing device needs repairs, whether it’s battery replacement, dust removal or recovery from a fall. Disassembling the Mi 4 is not an easy task: there is no removable back cover, and the body is glued around the perimeter, which requires accuracy and the right tools.

In this article, you'll find a step-by-step guide with photos of key steps, a list of tools you need, and warnings about typical errors that could damage the board or display. We'll look at both basic disassembly for battery replacement, and deeper dismantling for access to the motherboard. If you've never disassembled a smartphone before, don't worry: with the right approach, even a beginner can do the job.

Preparation for disassembly: tools and security measures

Before you start, make sure you have everything you need. Xiaomi Mi 4 has a single-piece metal body with adhesive connection, so you can’t do without specialized tools.

• 🔧 Plastic mediators (2-3 (a) - for separation of the body without scratches.
• 🔨 Thin asterisk screwdriver (T3, T4) — board-pin.
• 🔥 Dryer or thermo-air station - for softening the glue (temperature 60-80)°C).
• 🧲 Magnetic mat or container – to avoid losing small screws.
• 📱 Suction for screens - will help to smack the front panel.

Also, prepare your workspace: it should be clean, well-lit and free of static electricity. Put a soft cloth or rubber mat on the table to avoid slipping parts. If you're disassembling a battery replacement phone, buy an original battery with a capacity of 3080 mAh (BM43 code) in advance - cheap analogues can swell or quickly fail.

⚠️ Warning: Do not use metal tools to tamper with the body, this will lead to bullies on the aluminum frame. Also avoid overheating: if you heat the body with a hairdryer longer than 2-3 minutes, you can damage the display or glue under the battery.

Step 1: Remove the back cover and turn off the battery

Start by turning off your phone and retrieving it. SIM-And then the most important step is to separate the back cover from the display module, and because of the adhesive connection, you can't do this head-on, you need to heat it.

Turn on the dryer at medium power and evenly warm up the edges of the case (do not direct the air flow to the screen!). After 1-2 minutes, the glue will become softer. Apply the suction cup to the bottom of the screen (near the Home button) and pull up. Once the gap appears, insert a plastic mediator into it and carefully guide along the perimeter, separating the lid.

Warm up the body with a hairdryer (60–80°C)

Attach the suction cup to the bottom of the screen

Push the cover with a mediator from the left corner

Separate the cover around the perimeter without jerking-->

Once you remove the lid, you'll see the battery glued to the body, and before you continue, be sure to unplug the connector from the motherboard with a plastic mediator or tweezers, which will prevent short circuits from breaking down further.

Step 2: Dismantling the motherboard and additional modules

Now that the battery is off, we can start removing the motherboard.

1. Unscrew 10 screws (T3 and T4) around the perimeter of the board. See the location below (screws of different lengths - remember where you were!).
2. Carefully tuck the board with a plastic mediator, starting from the upper edge (from the headphone jack side).
3. Disconnect the plumes: the display, the cameras, the Home buttons and the touch module. They are fixed by the latches — lift them up, not pull the wires!

Warning: The Home button plume is particularly fragile, and if it is damaged, the fingerprint scanner will stop working (in the Mi 4, it is built into the button).

Once the board is removed, you will have access to the speaker, vibrator and charging connector, which are mounted on individual screws and can be replaced separately, for example, if the phone does not vibrate, the problem is most likely in the engine (the detail costs ~300 rubles).

Step 3: Replacing the battery – nuances and tips

The battery in the Xiaomi Mi 4 is one of the most vulnerable places, and after 3-4 years of operation, it loses up to 50% of its capacity, and sometimes swells up. Replacing it requires caution: the battery is glued to the body with double-sided tape, and it can not be pulled out just like that.

Here's how to do it right:

1. Put a plastic blade on the side (not the center!) if it swells, don't prick it, it's dangerous!
2. Put a thin plastic card under the battery and slowly lead it along the case, separating the glue.
3. After extraction, clean the body of glue residues with alcohol or acetone.
4. Install a new battery and press it for 10-15 minutes (you can put a heavy book on top).

💡

If the new battery is not holding a charge, check the power controller on the motherboard. Often the problem is not the battery, but the BQ24192 chip, which is responsible for charging.

Once you have changed the battery, be sure to calibrate it: fully charge the phone, then discharge it before it turns off and recharge it to 100%, which will help the system correctly determine the capacity.

Step 4: Disassembly of the display module (for experienced)

If you need to replace the touchscreen or the display itself, you have to disassemble the module completely, which is more difficult than replacing the battery, because it requires working with fragile plumes and adhesives.

• 🛠️ The display and touchscreen in the Mi 4 are glued together, and they can only be separated using a thermophen and a thin string (a process called "display cutting»).
• 🔍 Before disassembling, check if the display is really the problem. Sometimes the artifacts on the screen are caused by a malfunction of the graphics chip on the board.
• 💰 The cost of a new display module for the Mi 4 — from 2500 to 4000 rubles. (depending on quality.

If you decide to replace, act as follows:

1. Remove the metal frame around the display (it is attached to latches and glue).
2. Warm up the module with a hairdryer (temperature 70-80 ° C) and gently insert a guitar string or a special cutter between the glass and the matrix.
3. Slowly move the string around the perimeter, separating the touchscreen from the matrix. Don't push too hard, you can damage the plumes!

⚠️ Attention: When disassembling the display module, there is a risk of damaging the backlight of the screen. If after assembly there are dark spots or the backlight flashes, then the LEDs on the lower edge of the matrix have been damaged.

Step 5: Building a Phone – How to Avoid Mistakes

Building the Xiaomi Mi 4 after disassembly requires as much accuracy as dismantling. Here is a proven algorithm that will help avoid typical problems:

1. Check all plumes for clutter or contaminants, wipe the contacts with alcohol if necessary.
2. Set the screws in reverse sequence. Rotors of different lengths -- if you mix them up, you can damage the board!
3. Stick the battery with double-sided tape (use the original 3M 9448A or similar).
4. Warm up the body with a hair dryer before fixing the back cover - this will help the glue to grip better.

Don't turn the phone on immediately after assembly. Wait 10-15 minutes for all connections to settle.

• 🔋 Does charging work (plug the cable and look at the indicator).
• 📱 Does the touchscreen react to touches across the screen.
• 🎤 Whether the microphone and speaker are working (record the voice note).

(1) Whether the battery is connected to the board.

(2) Are the contacts closed on the board (check for foreign objects).

3) Is the display plumes and Home buttons correctly installed.-->

Frequent problems after disassembly and their solution

Even with careful disassembly, there can be problems, and here are the most common ones and how to fix them:

If after disassembly there were artifacts on the screen (strips, flickering), most likely, the matrix or plume was damaged. In this case, a diagnosis will be required in the service center - self-repair can aggravate the problem.

Another common mistake is tug-of-war screws, if you twist them too hard, you can damage the tracks on the board or crack the body. Use a screwdriver with a torque limiter (or twist the screws "to the end" without exerting effort).

FAQ: Answers to popular questions