Xiaomi Redmi 9A has become one of the most popular budget devices on the market due to its availability and reliability. However, like any gadget with a lithium-ion battery, it loses capacity over time, leading to quick discharge and unexpected shutdowns. If your phone stops holding charge or turns off at 20-30% charge, this is a sure sign that the battery life is exhausted.
Self-replacement is a great way to extend the life of the device without going to an expensive service center. The procedure requires accuracy and a minimal set of tools, but saves a significant amount. It is important to understand that the tightness of the case will be impaired if you do not use quality glue or B-7000, but the functionality will be fully restored.
In this article, we will take a look at the entire process, from the workspace to the final checkup, how to safely open the plastic back cover without damaging the plumes, and how to properly disable the battery to avoid short circuits on the board. Restoring autonomy will restore your smartphone to its former frolicity.
Tools and workplace preparation required
Before starting to disassemble the Redmi 9A, you need to organize a clean and well-lit space. Dust and static electricity are the main enemies of electronics, so it is recommended to wipe the table with a wet cloth and cover it with an antistatic mat or a regular sheet of paper. Also make sure that you have all the necessary tools at hand to not interrupt the process of finding the right screwdriver.
For a quality replacement, you will need a specific set that is often sold with a new battery, but it is better to prepare professional analogues. Plastic mediators are mandatory, since metal can damage internal components or scratch the frame. Heat treatment of the adhesive layer is a critical step, without which opening the case can lead to cracks.
- 🔧 Screwdriver kit: cross (PH000 or PH00) flat-work.
- 🔥 A hair dryer or heating platform to soften the glue under the cover.
- 🛠 Plastic spatula (mediator) and suction cup for neat opening.
- 🧴 Clay. B-7000 or special adhesive tapes to fix the new battery.
- 🧤 Antistatic gloves and tweezers for working with small details.
You should pay special attention to the status of the contact group of the new battery. Before installing, check its voltage with a multimeter, if possible, to make sure that the part is working. Remember to completely discharge the old phone before starting work or, conversely, discharge it to a minimum to reduce the risk of fire in case of accidental battery damage.
⚠️ Warning: Never start disassembling if the battery is swollen, in which case heating with a hairdryer can cause it to ignite or explode. A bloated battery should be removed with the utmost care, having previously punctured it with a needle away from flammable objects, although safer practice is cooling and careful extraction without puncture.
The process of safely opening the smartphone body
The back cover of the Xiaomi Redmi 9A is made of polycarbonate and is attached to a two-part glue around the perimeter. To open it, you need to warm up the edges of the device evenly. Use a dryer at medium temperature, driving the air jet along the circuit for 2-3 minutes. Do not hold the hair dryer at one point for too long, so as not to melt the plastic or damage the matrix of the screen on the back side.
After heating, insert the suction cup into the bottom of the back panel, closer to the logo, and slightly pull upwards, creating a small gap. In the resulting gap, carefully insert a plastic mediator. Movements should be sliding along the body, not pointing upwards, so as not to break the clips or the plastic itself. Thin mediator blades allow you to reach the glue layer without causing visible damage.
Move around the perimeter, gradually separating the lid from the frame. If you feel strong resistance, stop and warm up the problem area again. Inside, next to the top edge, there is a plume that connects the main board to the side button on and volume, so you need to act with extreme caution at the top. Mechanical effort is unacceptable here.
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To make it easier, you can use a thin line or a special string, by running it under the lid and moving it from side to side, like cutting a cake, which reduces the risk of plastic latches breaking.
When the lid is completely detached, put it in a safe place, and you will see the interior of the smartphone, closed by a plastic frame-holder of components, and this frame is also glued and secured with screws, which requires further careful attention.
Dismantling the protective frame and access to the battery
Inside the Redmi 9A, you'll see a black plastic frame that covers the battery and the bottom of the motherboard, which is fixed by multiple screws of different sizes and adhesive layers, and you'll need to unscrew all the visible screws using a magnetic screwdriver to keep them from losing them among the small parts.
Short screws are screwed into some holes, long screws into others, if you confuse them when you build them, you can break through the body or damage the internal components, systematize the fasteners by laying out the screws in the order in which you twisted them, or use a magnetic mat with markings.
Once the screws are removed, the frame needs to be carefully tampered with a mediator, it's held on a glue, so it may require a light warm-up with a hairdryer, move from the edges to the center, gradually peeling off the plastic, and underneath the frame is a plume that goes to the main board, which needs to be turned off before the plastic is completely removed.
☑️ Checking before removing the framework
Disconnect the sub-board flex cable that runs under the frame, it's connected to the main board through the connector, use a plastic blade or nail to plug the connector upwards, and the metal tools are best avoided here, so as not to close the contacts on the board.
Disconnecting the old battery and removing the element
The battery in Xiaomi Redmi 9A takes up most of the internal volume and is glued to the body with special adhesive strips. Before you try to remove it, you must necessarily disconnect the battery connector from the motherboard. This is the paramount security measure that shuts down the device.
The connector is on the top, under a protective metal or plastic plate (screen). Carefully bend the plume if it interferes with access, and disconnect the connector. Now that the power is off, you can start removing the battery itself. The glue under the battery is very strong, so you can't just pull it, it can burst.
- 🔥 Again, slightly warm up the battery area with a hairdryer through the back cover (if you haven’t removed it far yet) or directly in the case.
- 🎣 Use special exhaust strips (if they were pasted by the manufacturer in advance) for easy extraction.
- 💳 If there are no tapes, gently slide the plastic card under the battery and, swaying, cut off the glue layer.
- 🚫 Do not use metal objects in order not to puncture the battery shell.
In the process of retrieval, try not to deform the new battery if you have already taken it out of the package. Lithium polymer cells are sensitive to impacts and punctures. The integrity of the shell is the key to the fire safety of your future device.
⚠️ Warning: If you smell an electrolyte or see smoke during the extraction process, stop working immediately, take the device outside and fill it with sand.
Installation of a new battery and assembly of the device
After successfully removing the old battery, clear the seat of the old glue residue. Use soft cloth soaked in alcohol or a special cleaner. The surface must be clean and defatted to securely fix the new cell. It is advisable to paste bilateral tape on the new battery or apply a thin layer of B-7000 glue.
Install the new battery in the case, matching it with the connector on the board. Don't plug the connector to the end at once - first make sure that the battery is flat. Then gently press the connector until the characteristic click. Make sure that the plume is not squeezed and lies in its channel.
Now you can put the plastic frame back in place. Put a thin layer of glue around the perimeter of the frame or use new adhesive tapes. Press the frame and let the glue grab for a few minutes. Twistle all the screws into their seats, keeping the order you remembered when you disassembled. The timing of the screws tightening should be average, so as not to break the thread in the plastic.
| Assembly stage | Key action | Tool. | Important detail |
|---|---|---|---|
| Fixing the ACB | Applying glue/scotch | Glue B-7000 | Do not glue the connector |
| Connection | Docking of the plume | Finger/Shovel | You should hear the click. |
| Establishing a framework | Sticking and screws | Screwdriver PH00 | Watch the plumes. |
| Closing the lid | Final pinch | Rubber/Cargo | Hold for 2-4 hours |
The last step is to put the back cover in place, apply the glue around the perimeter of the case, apply the lid and press it tightly, and for better adhesion, you can wrap the phone with a cage gum or put it under a small load for a few hours, and the polymerization time of the adhesive is 2 to 24 hours depending on the conditions.
What if the phone doesn’t turn on after assembly?
Initial start and calibration of the new battery
Once the glue is finally assembled and dryed, you can start the first run. Connect the original charger and wait for the charging indicator to appear. If the screen catches fire and shows the charging process, the operation is successful. Don't turn the phone on right away, let it get at least 10-15% charge.
To properly operate the system and display the real percentage of charge, it is recommended to calibrate. Completely discharge the phone before turning it off, then charge it to 100% when it is turned off. Then turn on the device and, if the charge is less than 100%, finish it again. The calibration cycle helps the power controller correctly assess the capacity.
In the early days of use, watch for the heating of the case. Light heat when charging is normal, but heavy heating indicates problems with contacts or the quality of the battery itself. If everything went smoothly, your Redmi 9A is ready for active work again.
⚠️ Warning: If the phone turns on but discharges quickly or shows an incorrect percentage of charge (for example, jumps from 80% to 20%), you may have a defective battery or a poorly connected connector.