Modern flagship smartphones like the Xiaomi Mi 9 are complex engineering designs where every millimeter of interior space is used with maximum efficiency. The need to open the case can arise for various reasons: battery failure, damage to the screen after a fall or breakage of the charging connector. Unlike budget models, disassembly of the Mi 9 requires high accuracy, since the device does not have classic screws on the bottom edge, and the rear cover is glued around the perimeter.
Before you start physical intervention, it is important to understand that self-disassembly automatically voids the warranty. If your device is still in warranty service, it is wiser to contact an authorized service center. However, if the warranty has expired or the damage does not fall under the warranty case, carefully following all the steps will bring the device back to life. The main difficulty is the glass rear panel, which easily cracks with inept heat.
To successfully perform the procedure, you will need not only a set of tools, but also patience. The process takes an average of 30 to 60 minutes, depending on the experience of the master. Do not rush, especially during the stages of unplugging the lid and disconnecting the plumes, since sudden movements can lead to irreversible damage to the internal components. The heating temperature of the rear cover should not exceed 90-100 degrees Celsius, so as not to damage the oleophobic coating and adhesive layer.
Tools and workplace preparation required
Quality training is half the success of the whole operation. You will need a specialized set of tools that will allow you to work with small parts without damaging them. Using improvised tools such as kitchen knives or thick needles is strongly discouraged, as they can damage internal plumes or break the battery.
The main tool for separating the body will be a heating element, it can be a professional heating pad, a temperature-adjusted thermophen, or even a household electric stove (with caution). To peel off the lid, you will need thin metal blades or special suction cups. Also, there is a set of Torx T4/T5 and Phillips screwdrivers, since the screws inside the smartphone have different types of hats.
- 🔧 A set of precision screwdrivers with magnetic tips for twisting screws of different caliber.
- 🔥 Heat source (thermophene or heating pad) for softening the factory glue under the back cover.
- 🧤 Thin mediator, plastic card or metal spatula for neat opening of the body.
- 🧲 Magnetic mat or organizer for sorting screws, so as not to confuse them when assembling.
- 🧴 Isopropyl alcohol or special solvent of glue (B-7000) final-clean.
The organization of the workspace is critical: the surface should be clean, well-lit and not conduct static electricity. It is recommended to use an antistatic mat. Before starting work, be sure to turn off the device. If the smartphone does not turn on due to damage, try to discharge the battery as much as possible before heating to reduce the risk of fire in case of accidental puncture.
☑️ Preparation for disassembly
Removal of the rear glass panel
The riskiest step is to separate the back cover. In the Xiaomi Mi 9, it is made of glass and planted on double-sided tape around the perimeter. The heating must be done evenly, paying special attention to the edges of the device. Keep the phone on the heating element for about 3-5 minutes, periodically checking the temperature with your finger - the glass should become hot, but not scalding.
⚠️ Warning: Never insert metal tools deep inside the case immediately after heating.The adhesive may soften unevenly, and a sharp movement of the shoulder blade may break the glass or damage the wireless charging plume that is glued to the inside of the cover.
After sufficient warming up, use a suction cup to create a small gap between the frame and the lid. If there is no suction cup, you can carefully insert a thin blade into the tray area. SIM-card USB, But you have to be very careful, and you have to put a mediator in the gap, and as you move along the perimeter, you have to gradually cut through the adhesive layer.
Pay special attention to the bottom of the smartphone, where the speaker and the charging connector are located. The adhesive layer is often thicker here. Once the lid is separated, don't try to remove it completely. Open it as a book to access the screws that lock the protective plate. Often the lid is additionally held on the glue in the area of the camera, so check all the corners.
What to do if the glass is cracked?
Dismantling protective plates and disconnecting plumes
When you remove the back cover, you'll see the interior of the smartphone, and most of the space is occupied by a battery, but access to it is blocked by plastic and metal slats. The Xiaomi Mi 9 uses a complex system of screws of different lengths, so it's critical to remember or photograph the location of each.
The first thing you do is unscrew the screws that lock the bottom plastic lining that covers the speaker and the bottom board, and then you remove the central metal plate that hides the connectors of the motherboard and battery, which is usually mounted with 6-8 screws around the perimeter, and use a magnetic screwdriver to keep the screws from dropping inside the case.
The next step is to turn off the power. This is the most important rule of electronics: Find the connector of the battery plume and carefully disconnect it with a plastic blade or nail, and only after the power out can the other plumes be turned off: the display, the main and front cameras, and the connectors of the lower board.
- 🔌 Disconnect the plume of the main camera module, which is located at the top of the motherboard.
- 🔋 Carefully tuck the battery connector, making sure that the plume itself has not been damaged.
- 📱 Turn off the display plume, which is usually in the central part of the board.
- 📡 Remove the antenna module NFC, if it interferes with access to the screws of the central plate.
When working with plumes, avoid breaking the contacts. If the connector has a metal latch, it must be bent beforehand. Once all connections are turned off, you can remove the central protective plate, below which you will see the motherboard and the top of the battery.
Replacement of the battery and work with the glue layer
The battery in Xiaomi Mi 9 takes up a significant part of the volume and is glued to the frame of the case. It just can not be pulled out - you need to reheat. Turn on the thermophen or put the phone on the heating pad with the front side down (pre-protecting the screen from scratches) for 5-7 minutes. The glue should become plastic.
Use special hoods with suction cups or a thin line/plastic map to extract the battery. Run a line under the edge of the battery and walk through the battery area with sawing movements, cutting the adhesive layer. It is strictly forbidden to use metal tools to tamper with the battery, since puncture of the shell will cause lithium to ignite.
Once the old battery is removed, you need to clear the seat of the residue of the old glue. Use isopropyl alcohol and a plastic card. The surface should be perfectly smooth and clean so that the new battery will lie flat and hold secure. Apply a new double-sided tape or special glue B-7000 thin layer.
| Component | Type of attachment | Difficulty withdrawal | Risks. |
|---|---|---|---|
| Back cover. | Perimeter adhesive layer | Tall. | Breaking glass, damage to charging plume |
| Battery | Glue all over the area | Medium | Battery puncture, fire. |
| Protective plates | Torx/Phillips screws | Low. | Loss of screws, length confusion |
| plumes | Connectors (latches) | Medium | Contact break, latch break. |
Install a new battery with it tightly pressed over the entire surface to fix the glue. Connect the battery plume to the motherboard. Don't turn the phone on right away -- assemble the device at least partially first to check if it works. Make sure the phone responds to the charger and shows the correct charge.
Assembly of the device and verification of functionality
The assembly is done in reverse disassembly. Put all the protective plates in their place, making sure that no screw is left over. Twisted the screws without undue effort, so as not to break the thread in the plastic bushings of the frame. Pay special attention to the plume of wireless charging — it should lie exactly in its niche.
Before you finally stick the back cover, do a test. Turn on your smartphone and check the touchscreen, cameras, speakers, microphone and communication modules. If everything works correctly, you can apply new glue to the frame of the case. Use a thin strip of special glue or a ready-made glue circuit.
⚠️ Warning: When installing the back cover, make sure the wireless charging plume is not caught under the edge of the glass and will not be squeezed.This may cause the charging module to short or fail.
Press the back cover with rubber harnesses or a weight for 15-20 minutes to primary polymerize the glue. It takes about 2-4 hours to dry completely. It's best not to use the phone actively. After assembly, wipe the case from fingerprints and glue residues.
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Use new screws if the old ones have tattered hats or rust, which will ensure that the internal components are fixed reliably and will make future repairs easier.
Typical errors and precautions
Even experienced craftsmen make mistakes, so it's important to be aware of the typical problems, one of the most common is the damage to the plume of the underscreen fingerprint scanner when the battery is sloppy, which is very fragile and requires delicate handling, and users often forget to remove the protective film from the new battery, which leads to poor contact or bloating.
Another common mistake is to use the wrong glue: Superglue (cyanacrylate) cannot be used: its vapors settle on the optics of cameras and sensors, causing them to become cloudy and fail. Use only specialized adhesives for electronics or double-sided tape.
If the phone doesn't turn on after assembly, don't rush to disassemble it again. Connect the device to the charger and wait 10-15 minutes. Sometimes a deeply drained battery takes time to activate. If the screen catches fire but the touchscreen doesn't work, check the density of the display plume.
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The main mistake of beginners is to ignore the order of turning off the plumes. Always turn off the battery first to avoid short circuit on the board.