The Xiaomi Redmi Note 8 Pro, released in 2019, has established itself as one of the most popular gadgets thanks to the powerful MediaTek Helio G90T processor and quality camera. However, like any device with a lithium polymer battery, it loses capacity over time, requiring a replacement power source. If your phone stops holding charge, turns off 15-20% or swells, lifting the back cover, it’s time for repair.
Self-replacement is a real way to save a significant amount, as service centers often cost half the cost of a new battery. The process requires accuracy, a set of special tools and an understanding of the design of a modern smartphone, where the back cover is glued to, rather than removed mechanically. In this article, we will discuss in detail each step, from preparation to first charging.
Before you start disassembling, you need to make sure that the problem is the wear of the battery chemistry, and not a software failure or malfunction of the power controller. Visual inspection for bloating and a sharp drop in autonomy are the main signs. If you are ready for the procedure, be patient, since the Redmi Note 8 Pro has a fairly dense layout of internal components.
Tools and workplace preparation required
You can't repair quality without proper preparation. You'll need not only a new BM4B battery (original or quality analogue), but also a specific toolkit. Working with adhesives and brittle plumes requires precision tools that often come with remakes, but it's better to have professional counterparts.
Organize the workplace so that all the parts are at hand, and the lighting allows you to see small screws and connectors. Magnetic substrate or a sheet of paper with markup will help you not to confuse fasteners of different lengths, which is critical for the safety of the motherboard.
- 🔧 Screwdrivers: cross (Phillips #00, #0) and flat for neat tweaking.
- 🔥 Dryer or heat heater (to soften the glue under the cover).
- 💳 Plastic cards or mediators for opening the body without damage.
- 🧲 Magnetic mat or organizer for screws.
- 🧴 Isopropyl alcohol and sucker for working with adhesive layer.
⚠️ Warning: Before starting work, be sure to turn off your smartphone. Working with a connected battery when unscrewing metal screens can lead to a short circuit and failure of the power controller.
☑️ Preparation for repairs
Rear cover removal process
The most challenging and risky step is to remove the glass back panel. In the Redmi Note 8 Pro, it is held on a powerful perimeter adhesive layer. The heating must be uniform so that the glass does not crack from the thermal shock, but the adhesive has softened enough to open.
Use a dryer by warming up the edges of the device for 2-3 minutes. Don't keep the jet of hot air in one spot for too long, especially around the cameras and the speaker. After warming up, use a suction cup to create a small gap, and carefully enter a plastic card or mediator.
Move the map along the perimeter, gradually cutting through the adhesive layer. Be especially careful in the bottom, where the fingerprint scanner plume passes, which is glued to the lid. A sharp jerking motion can break this plume, and the unlock function will stop working.
What to do if the lid is cracked?
Disabling plumes and removing protective screens
Once you successfully remove the lid, you will see the inside of your smartphone, immediately disconnect the fingerprint scanner plume if it's still connected to the board, and then dismantle the plastic frame that hides the main connectors and the camera module.
Unscrew all visible screws that lock plastic and metal screens. Note that some screws may be hidden under stickers or warranty seals (unless the phone has been opened before).
Use a plastic blade or nail to turn off the plumes. Metal tools are undesirable here, as you can damage the contact areas on the board. First, the battery is turned off, then all other peripheral plumes (display, underscreen camera, charging boards).
- 🔌 Disconnect the main battery plume from the motherboard.
- 📷 Carefully remove the main camera module if it interferes with access.
- 🔋 Unscrew the screws fixing the control board (bottom part).
- 🧩 Remove the vibrator and speaker if they block access to the battery.
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Before turning off any plume, it is recommended to take a picture of its position and path of the gasket, which will help to put them back correctly, avoiding overburdens and clamps.
Removal of the old battery
In the Xiaomi Redmi Note 8 Pro, the battery is attached to double-sided tape, which over time becomes polymerized and becomes very durable. You can’t just “knock out” the battery — there is a high risk of damage to the shell, which will lead to fire or chemical burns.
For safe extraction, use a special suction hood or, in extreme cases, a thin line / tooth thread. Strip under the battery and saw in adhesive movements from left to right, gradually moving inwards. Also effective isopropyl alcohol, which you need to drip under the edges of the battery and wait 5-10 minutes.
Do not use metal objects (knives, screwdrivers) to smear the battery. The lithium-polymer cell shell punctures instantly and emits heat and smoke. If the battery is swelling, act with double caution, as its shell is thinned.
| Parameter | Meaning | Note |
|---|---|---|
| Model battery model | BM4B | Standard for Note 8 Pro |
| Capacity | 4500mAh | Typical container |
| Tension. | 4.4V / 3.85V | Nominal voltage |
| Type | Li-Po | Lithium-polymer |
Installation of a new battery and assembly
Before installing a new power source, carefully clean the seat of old glue residues. Use alcohol and a plastic card. The new battery (if it does not have factory tape) must be glued to special adhesive tapes or use B-7000 glue, but only point-by-point, so as not to complicate future replacement.
Connect the new battery connector to the motherboard. Don't plug the plume before the click immediately - first make sure the contacts match perfectly. Once connected, you can check the health by briefly pressing the power button (the rest of the plumes can be turned off, the screen will not burn, but the phone must react with vibration).
The assembly is done in reverse order. Make sure that all the plumes are in their channels and are not clamped by metal screens. Pay special attention to the plume of the fingerprint scanner, it should be connected tightly and smoothly.
⚠️ Warning: Don't stick the back cover dead. First, turn on your phone, check the sensor, cameras, sound and charging. Only when you're sure it's fully functional, apply a new glue or tape.
First launch and calibration
After final assembly and sealing of the housing, the first charge cycle is required.New batteries often come with a charge of about 40-60%, but for the controller to function properly (BMS), it is recommended to discharge the device before turning off, and then charge to 100% when off.
The calibration process helps Android system correctly display the percentage of charge. Without this procedure, the indicator can "jump" or show incorrect data. In the first days of use, try not to overheat the smartphone, allowing the battery chemistry to activate.
If the phone doesn't turn on or see charging after you've replaced it, check the connection quality of the battery plume. Sometimes you need to reconnect the connector several times to make the contacts fall into place. Also check the integrity of the plume itself for microcracks.
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A good battery calibration is key to properly displaying the charge and long-lasting life of the new battery. Don't ignore the first full charge-discharge cycle.