Replacing the battery on Xiaomi Mi 9T with your own hands: a detailed guide

Smartphone Xiaomi Mi 9T, It is known as the Redmi market. K20, It has proven itself as a device with excellent AMOLED-After a few years of active use, owners often face rapid discharge, sudden shutdowns at 20% charge or battery bloating, which requires immediate intervention. Self-replacement of the power supply is a real opportunity to extend the life of the gadget without overpayment in service centers, where the cost of work can be up to half the price of a new part.

Before you start dismantling, you need to be aware of the risks associated with leakage of the case and work with lithium polymer components. Safety in this process is the first, as damage to the battery shell can lead to its ignition or even explosion. In this article, we will discuss in detail all the steps, from the preparation of the workplace to the final calibration of the system, so that you can perform the procedure as efficiently as possible.

It is important to understand that the Redmi K20 has a design without a mechanical fingerprint button on the back, which makes it easier to dismantle the back cover compared to models with a scanner at the rear, but requires accuracy when working with the adhesive layer. The success of the operation depends on the quality of the tools used and the patience of the master, so do not rush and neglect precautions for the sake of speed.

Tools and workplace preparation required

Quality repair is impossible without proper tools, and trying to open the smartphone with improvised means like knives or forks is almost guaranteed to damage the body or internal plumes. You will need a specialized kit that includes a suction cup for lifting glass, a set of screwdrivers with cross bits of different sizes, a plastic shovel (mediator) and tweezers with curved ends for working with small screws.

Particular attention should be paid to heating equipment, as the factory glue that fixes the rear panel softens under the influence of temperature, allowing you to open the device without chipping. For this purpose, a temperature-adjusted thermophen or a special heating pad for smartphones is ideal, although in extreme cases you can use a household hair dryer if you keep it long enough at maximum mode.

⚠️ Warning: Never heat the back cover at one point for too long, especially in the area of the display plumes, so as not to damage the matrix or detach the polarizing layer of the screen.

Besides tools, prepare the screw sorting containers, as the Xiaomi Mi 9T uses different lengths of fasteners, and mix them up very easily. Also, don’t forget about isopropyl alcohol and new adhesive tapes (B-7000 or finished frames) that will ensure the housing is tight after assembly.

Rear cover removal and access to the insides

Redmi's autopsy process K20 It starts with the removal of the tray for SIM-cards, which is a standard procedure for all modern smartphones and avoids accidental damage to the slot during heating. After that, the device must be heated around the perimeter to a temperature of about 80 degrees, evenly distributing heat so that the glue becomes plastic, but does not flow inside the body.

Use a suction cup to create a small gap between the glass and the frame, and gently insert a plastic blade, leading it along the edges, trying not to touch the tail of the side button and the main camera module. The back cover in this model is quite brittle, and any excessive force can lead to cracks, so act slowly and feel the resistance of the material.

• 🔥 Heat the perimeter of the device during 3-5 minutes before hand comfort.
• 🔧 Finish the cover with a mediator at an angle of no more than 30 degrees to the plane of the body.
• 🚫 Avoid deep penetration of the tool in the upper left corner, where the plumes are located.
• 🧴 With strong resistance, add a drop of alcohol to the gap to dissolve the glue.

After successful separation of the glass, put it in a safe place, before rubbing it from the residue of the glue, so that it does not interfere with the reverse assembly. Now you have access to the main board, battery and camera module, but you should not rush to remove the protection.

Disconnection of plumes and removal of protective plates

Inside the case Xiaomi Mi 9T, you will see a metal plate covering the connectors of the plumes, which is attached with several screws around the perimeter and in the center. Unscrew them, you need to carefully remove the plate with tweezers, trying not to catch thin plumes going to the bottom board and camera module.

The first thing you do is you turn off the battery plume, which turns the device off and makes it safe for electronics to do that, and then you can disconnect the main plume of the display and the bottom board, using a plastic blade to tweak the connectors upwards, rather than sideways, so you don't break the contacts.

Next, you need to unscrew all the screws that lock the plastic frame of the speaker and the bottom of the body to gain full access to the end of the battery, in some cases, you will need to remove the vibrator motor, which can block access to the lower edge of the battery.

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Before disabling any plume, take a picture of its position and condition so that during the assembly there is no doubt which connector should be connected to.

Removing the old battery and installing a new one

The battery in the Xiaomi Mi 9T (BM4L model) is fixed to double-sided tape throughout the area adjacent to the middle frame, making it difficult to extract without damage. It is strictly forbidden to try to tamper with the battery with metal tools, since puncture of the shell will lead to instant failure and possible fire.

Heat the battery area to 60-70 degrees to soften the glue, and use a thin line or a special plastic card to carefully cut the adhesive layer, making movements from side to side. This process takes time and patience, because the lithium polymer cell is very sensitive to mechanical stress.

⚠️ Warning: If the battery is swollen, handle it with extreme caution, do not squeeze it or pierce it, as there are toxic gases inside, dangerous to health.

After removing the old battery, clean the seat of glue residue with alcohol and paste new strips of bilateral tape or use a special B-7000 adhesive with a thin layer. Set the new battery, press it tightly throughout the area and let the glue grab for 10-15 minutes before continuing assembly.

• 🧹 Carefully degrease the surface of the frame before sticking the new element.
• ⏱️ Let the glue or sealant dry the manufacturer's specified time.
• 🔋 Make sure the new battery connector sits tightly in the connector.
• 🧤 Work in antistatic gloves or touch metal to remove statics.

Assembly of the device and checking leakage

The Redmi K20 is assembled in reverse order, but it is important to remember to connect the plumes before installing metal protective plates to avoid damage to the screws. First connect the battery, then the display and the lower board, then install all metal screens in their places and twist the screws.

Pay special attention to applying glue to the back cover: use a thin frame or carefully apply the sealant around the perimeter, avoiding getting into the camera and sensors. Press the cover with rubber harnesses or load for 30-60 minutes to ensure maximum adhesion and restore moisture protection as possible at home.

Once fully assembled, turn on the device and check the touchscreen, cameras, speaker and communication module, as sometimes the plumes may not be fully connected the first time. If all functions are working correctly, you can proceed to calibrate the battery to correctly display the percentage of charge.

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High-quality sealing of the back cover is not only protection against dust, but also a guarantee that the display will not peel off when heated during operation.

Calibration of the battery and elimination of typical errors

After the battery is replaced, the power controller may not correctly display the charge level, showing, for example, 100% immediately after turning on or turning off at 30%. To eliminate this problem, it is recommended to conduct a full calibration: discharge the phone until completely turned off, then charge when off to 100% and hold for another hour.

Sometimes users encounter a “Battery communication error” or cyclic reboot immediately after replacement, which most often indicates poor connector contact or damage to the plume during installation, in which case you need to reopen the device, check the purity of the contacts and the density of the connectors.

If the phone is warming in the battery area even in a simple one, this may indicate an internal short circuit in the new element or a problem with the charge controller on the board, in which case use of the device should be stopped and additional diagnostics with the multimeter should be carried out.

⚠️ Warning: Do not use your phone during the first charge after replacement to avoid overheating and ensure that the charge is evenly distributed across the cells.

Frequently Asked Questions (FAQ)