Replacement of the battery on Xiaomi Mi9 SE: instructions with photos and videos

Xiaomi Mi9 SE is one of the most popular smartphones of 2019, but even after 3-4 years of active use, the battery begins to “set” in half a day, and sometimes completely shut down at 30% charge. If you notice that the phone discharges too quickly, heats up when charging or suddenly turns off, it’s time to think about replacing the battery.

In this article, you will find a step-by-step guide to replacing your battery with a Mi9 SE with a photo, a list of tools you need, and tips for choosing a quality battery. We will also tell you how to check the wear of an old battery, avoid disassembly errors, and what to do if the phone does not turn on after replacing. If you have never disassembled your smartphone, don’t worry: with the right approach, even a beginner can cope in 30-40 minutes.

Important: the procedure requires care, as the Mi9 SE has a fragile display cable and adhesive battery. If you are not sure about yourself, you should contact the service center.

How to know if the Xiaomi Mi9 SE battery is time to change?

Before you start the screwdriver, make sure the battery is the problem.

• 🔋 Phone's running out of power. 2-3 hours with moderate use (social networks, messengers).
• 🔥 The body heats up strongly during charging or playing.
• ⚡ Charge jumps (for example, from 50% immediately to 20% or the phone turns off at 30%).
• 🛑 Notification "Battery damaged" in settings (Settings) → Battery status).
• 📉 The Autonomous Work Time has been reduced in 2-3 compared to the new phone.

If you have at least 2-3 points of the same, the battery is worn out. For accurate diagnostics, you can use applications like AccuBattery (reveals real capacity) or built-in statistics in Settings → Battery → Battery Use. If the capacity has fallen below 70% of the factory capacity (3070 mAh), it is time to act.

Tip: Before replacing, try calibrating the battery -- completely discharge the phone before turning off, then charge to 100% without interruption -- sometimes it helps to get the exact charge reading back, but it won't solve the wear problem.

What tools are needed to replace them?

To replace the battery with the Mi9 SE, you will need a minimum set of tools that can be bought on AliExpress or in electronics stores for 300-500 rubles.

In addition, the following may be useful:

• 🧲 Magnetic mat or screw tray (so as not to lose).
• 🔦 Lupa or flashlight (for small details).
• 🧴 Double-sided tape or glue B7000 (if you need to glue a new battery).

⚠️ Warning: Do not use metal blades or knives - they can damage plumes or body. Also avoid overheating with a hairdryer (maximum). 60-70°C), otherwise the screen or battery is deformed.

Check the battery capacity in AccuBattery|Buy a new battery (original or high-quality analogue)|Prepare the workplace (clean table, good lighting)|Backup of data (in case of errors)|Charge the phone before 30-50% (safe)-->

What battery to choose for Xiaomi Mi9 SE?

The battery quality depends on how long your phone will last after you replace it. There are three options on the market:

1. The original Xiaomi battery (article MBJ4066 or MBJ4067) is the most reliable, but expensive (1500-2500 rubles.) It is sold in branded services or on official sites (Mi Store, AliExpress from trusted sellers).

🔍 How do you authenticate? The original battery should have:

• 🏷️ Hologram with Xiaomi logo and serial number.
• 📦 Packaging with protection against counterfeiting (check code on the Xiaomi website).
• 🔧 Correct marking: MBJ4066 3.85V 3070mAh.

⚠️ WARNING: If you buy a battery on AliExpress or Wildberries, read the reviews with the photo! Often sellers send fakes with capacity. 2000-2500 mAh instead of the stated 3070 mAhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh.

Step-by-step: how to change the battery on Xiaomi Mi9 SE

Now, to the most difficult part, disassembling the phone, follow the instructions carefully so that you don't damage the plumes or the screen.

Step 1: Turn off the phone and remove the back cover

1. Turn off the Mi9 SE completely (press the power button and select “Switch off”).

2. heat the screen edge with a hair dryer (30 seconds on each side) - this will soften the glue. Keep the hair dryer at a distance of 5-7 cm so as not to overheat.

3. With a suction or tape, gently tuck the screen from the bottom edge (near the USB-C connector). Insert the plastic blade into the slot and slowly lead along the case, separating the glue.

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If the screen doesn't respond, warm it up again with a hair dryer. Don't force it, you can damage the display cable!

Step 2: Disconnect the battery plume

1. Unscrew 5 screws holding the metal plate over the battery (use the PH00 screwdriver).

2. Carefully gently put a plastic blade on the battery plume (it is on the right of the battery, under the black tape).

⚠️ Warning: Do not touch other plumes (especially the display one) - they are fragile and can come off!

Step 3: Remove the old battery

1. There are adhesive strips under the battery. Pull carefully behind them (if they do not come off when the lid is removed).

2.If the glue is too strong, drop a little isopropyl alcohol under the battery - it will dissolve the glue in 1-2 minutes.

3. Remove the battery without bending it. If it swells, don't puncture it!

Step 4: Install a new battery

1. Clear the place under the battery from the residues of glue with alcohol.

2. glue a new battery (use double-sided tape or B7000 glue).

3. Connect the battery plume to the motherboard and fasten the metal plate with screws.

Step 5: Get your phone together

1. Make sure all plumes are connected (display, camera, power button).

2. Stick the back cover. Warm it up with a hair dryer (so that the glue will better grasp).

3. Turn on the phone and check the charge. If everything works, calibrate the battery (discharge to 0% and charge to 100%).

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The most common mistake when replacing is damage to the display plume. Always use plastic shoulder blades and take your time!

What if the phone doesn’t turn on after the replacement?

If the Mi9 SE does not respond to the power button after assembly, do not panic.

• 🔌 Battery plume is not connected – take the phone apart and check the connection.
• 🔧 Remove the display plume - gently press it or replace it (if it breaks).
• 🔋 New battery discharged - connect charging to 10-15 minutes, then try to turn on.
• 📱 Short-circuit protection is triggered – disconnect the battery for 1 minute, then plug again.
• 🔥 Overheating or damage to the board – if the phone warms or smells of a burn, bring it to the service.

If nothing helps, try a forced start:

1. Connect the charger.
2. Press the Power button + Volume up for 10-15 seconds.
3. If the Xiaomi logo appears, release the buttons.

⚠️ Warning: If the phone is turned on but not charged, check USB-Ports to pollute or damage contacts, often after disassembly, dust gets in.

How much does it cost to replace the battery in the service?

If you don’t want to take risks and decide to give your phone to a workshop, here are the average prices for 2026:

💡 Advice: In the official service give a guarantee 6-12 You can save a few months on work and battery, but you can save a lot of money in small workshops, but you can run into a poor battery.

Before you give up the phone, ask:

• 🔧 What battery will be installed (original or analogue)?
• 📝 Is there a guarantee for the job?
• ⏳ How long will it take to repair?

How to extend the life of a new battery?

To make your new battery last longer, follow these rules:

• 🔌 Don't discharge until 0% — charge-range 20-80%.
• ⚡ Use the original RAM (or Quick Charge 4 support)+).
• 🌡️ Avoid overheating – Do not leave your phone in the sun or near heat sources.
• 📵 Do not play heavy games while charging - this accelerates wear and tear.
• 🔄 Calibrate the battery once in a while. 2-3 month (down to level) 0% charge up 100%).

You can also disable background processes and auto-update applications:

1. Go to Settings → Battery → Battery Optimization.
2. Turn on charge saving mode for unnecessary applications.
3. Turn off autosynchronization in Settings → Accounts.

⚠️ Warning: If you use wireless charging, remember that it heats the battery more than wired charging.

FAQ: Frequent questions about replacing the battery with Xiaomi Mi9 SE