Xiaomi Redmi Note 4 is one of the most reliable models in the company’s history, but even legendary devices wear out power components over time. If your phone stops holding a charge, turns off 20-30% or the body is inflated, replacing the energy source becomes inevitable. This process requires accuracy, but it is quite feasible at home with a minimum set of tools and understanding the architecture of the device.
Unlike modern monoblocks, where disassembly takes minutes, the design of the Redmi Note 4 (especially the version based on the Snapdragon processor) has its own nuances related to the location of the plumes and dense layout. Wrong actions can damage the display or plume of the fingerprint scanner, so it is extremely important to follow the proven methodology. In this article, we will discuss each step in detail so that you can safely return the gadget to factory autonomy.
Diagnostics of battery condition and workplace preparation
Before you start physically disassembling the case, you need to make sure that the problem lies in the wear of the chemical element, and not in the software failure or malfunction of the power controller. Visual inspection often gives more information than software tests: if the back cover has moved or the screen has started to bulge out of the frame, this is a sure sign of bloating. In this situation, it is strictly forbidden to operate the device, because there is a risk of fire or further destruction of the internal components.
You can use built-in system tools or third-party utilities to perform a high-quality diagnostic. Run the engineering menu by typing the dialer code ##6485##. Here you are interested in parameters. MB_06 (battery status; and MF_02 (If the status indicates "Bad" or the number of cycles exceeds 500-600, the replacement is inevitable.
⚠️ Warning: If you notice that the battery warms heavily during charging or the phone spontaneously reboots under load, do not delay repair.Using a bloated cell can damage the touchscreen or short circuit.
Preparing the workplace is critical to the success of the operation: You need a clean, well-lit surface, free of static electricity; prepare all the necessary tools in advance to avoid distractions; and avoiding dust and moisture is also a must, as getting debris under the display or into the connectors can be fatal to electronics.
Necessary tools and selection of components
The quality of the new battery directly affects the future autonomy of the smartphone. The market is full of fakes, so when buying, pay attention to the availability of holograms, the quality of font printing and the weight of the element. The original battery for the Redmi Note 4 (the BN41 model for the Snapdragon version) has a capacity of 4100 mAh. Buying cheap counterparts often leads to the fact that after a month of use, the capacity drops to 50% of the declared.
To disassemble the case, you will need a specific set of tools that can be purchased from any radio parts store or ordered online. A standard set of "cross" screwdrivers may not be enough, since screws of different types and sizes are used in the design.
- 🔧 Screwdriver kit: cross (PH000), flat and special triangular (Tri-wing) for screws under the display.
- 🔥 Hair dryer or heating platform: necessary to soften the glue fixing the back cover.
- 💳 Plastic card or mediator: for neat opening of the case without damage to the plastic.
- 🧲 Magnetic mat or organizer: for sorting screws, as they differ in length and threading.
Pay special attention to the suction cup to remove the lid. If you do not have a professional vacuum pump, use a regular glass suction cup, but act extremely carefully so that the back panel does not crack. It is also recommended to have isopropyl alcohol on hand to clean the surfaces of old glue.
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Use isopropyl alcohol 90% or higher to dissolve the glue. Water or alcohol of low concentration can cause corrosion of the contacts.
Body disassembly process and component dismantling
We're going to start the most important part of the process, the disassembly. SIM-Turn off the device, heat the back cover around the perimeter with a hair dryer to temperature. 60-70 The plastic must be warm, but not hot, so as not to deform. Insert the suction cup in the bottom of the lid, closer to the charging connector, and gently pull up while inserting the mediator into the resulting gap.
When you take the lid off, you'll see the internal layout, and in the Snapdragon version, the battery is covered with a metal plate that's screwed up with lots of screws, and in the MediaTek version, it's easier to access the battery, but it takes care to disconnect the fingerprint scanner plume, which is often glued to the lid.
☑️ Ready to remove battery
Next, unscrew all the visible screws that hold the motherboard and the protective plates, and remember to disconnect the main camera module plume and the antenna contacts, and then you can have full access to the battery compartment, and be careful, some screws may be hidden under stickers or rubber plugs.
The secret of screws under the frame
Use a plastic spatula to remove the old battery. Do not use metal tools such as tweezers or a knife, as one wrong move can penetrate the lithium-polymer cell shell and cause ignition. If the battery is glued to double-sided tape, warm up the area under it slightly with a hairdryer.
Installation of a new battery and assembly of the device
Before installing a new battery, compare it to the one you removed. The connector and dimensions should be exactly the same. If the new battery does not have an adhesive base, apply a thin layer of special glue B-7000 or use double-sided electronics tape, which will prevent the battery from moving and rattling inside the case when shaking.
Connect the battery plume to the motherboard before you click. Make sure the connector sits flat and tight. Now you can test the system without fully assembling the phone. Press the power button. If the screen catches fire and the MI logo, the connection is successful.
| Assembly stage | Key action | Risk of error |
|---|---|---|
| Connecting plumes | Clicking to the point | Unpressed contact, lack of charge |
| Battery stowage | Sticking on glue | Displacement, swelling due to pressure |
| Fixing fees | All screws rolling. | Loss of antenna contact |
| Closing the lid | Heating and pressing | Trying to close without heating the glue |
When assembling the body, make sure that no plume is pressed or laid at a sharp angle, especially the display plume and touchscreen. Carefully put all antenna wires into your channels. The back cover before installation is also recommended to warm up and apply a new layer of glue around the perimeter to restore tightness.
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Building quality is 90% of the longevity of a repair, and a poorly pressed lid will cause dust and moisture to enter, killing the new battery faster than wear.
Primary activation and calibration of the system
After a physical replacement, the system may not display the charge level correctly, because the power controller "remembers" the parameters of the old, degraded battery, and to reset this data and calibrate the system, you need to perform a series of actions immediately after the first switch on.
Discharge the phone until it's completely turned off (0%). Then charge it when it's off until it reaches 100%. Then turn on the device without disconnecting the cable, and wait until the indicator shows full charge again. Only after this procedure, the percentage readings will be accurate.
In some cases, you may need to reset battery statistics through an engineering menu or ADB-For the Redmi Note, but for the Redmi Note. 4 If the phone continues to behave strangely, check the voltage on the contacts of the battery with a multimeter - it should be within the range of 3.7-4.2 V.
Typical errors and troubleshooting
Even experienced craftsmen sometimes face unexpected situations. One of the most common problems after assembly is the lack of response to charging. Most often this indicates oxidation of the connector contacts or damage to the plume itself during replacement. Carefully examine the connectors under the magnifying glass.
Another common mistake is that screws that are tangled up when assembled can break through the motherboard, causing a short circuit. If the phone doesn't turn on after assembly, don't try to charge it aggressively -- better disassemble the device again and check that all the components are installed correctly.
⚠️ Warning: If your phone shows a “Fake battery” after replacing the battery or is constantly restarting, you may have found a defective copy with the wrong ID resistance.
Also worth mentioning is the problem of sticking buttons. If you don't build it neatly, the plug of the power button can be squeezed or shifted, and if the button doesn't get squeezed with a clear click, you'll have to take off the lid again and fix the mechanism.