Replacement of the back cover with Xiaomi Mi 9T: disassembly, tools and secrets of masters

Replacement of the back cover with Xiaomi Mi 9T — A challenge that many users are afraid of because of the fragility of the glass panel and the risk of damaging the internal components, but with the right approach and the right tools, you can do it yourself, saving you money on the service center. This model, released in 2019, is known for its retractable front module and premium design, but it is the glass back panel that most often suffers from falls or scratches.

Unlike budget smartphones with plastic covers, Mi 9T It requires a lot of care, because it uses perimeter tape, and it hides antenna contacts and plumes underneath the glass, and if you've never taken a smartphone apart, you'd better practice on a simpler technique or see a specialist. But if you decide to repair yourself - this instruction will help to avoid typical errors and maintain the operability of the device.

Before you start, assess the extent of the damage. Cracks on the glass without leakage can be temporarily "cured" with a protective film, but if the lid is moving away, creaking or moisture is visible under it, replacement is inevitable. Remember: non-original parts can worsen the network signal or work. NFC due to poor antenna tracks.

Training: tools and materials

Replacement of the back cover with Xiaomi Mi 9T You're going to need a specialized toolkit, and don't try to do it at hand, because it's almost guaranteed to damage the plumes or the body:

• 🔧 Plastic blades (2-3 - for tidy lids. Metal mediators are not suitable!
• 🔥 Hair dryer or thermo-air station - for softening the glue (optimum temperature 60-80)°C).
• 🧲 Suction - helps to evenly raise the glass after heating.
• 🔩 Screwdriver. T3 and T5 — mid-frame.
• 🧴 Isopropyl alcohol 90%+ — glue-residue.
• 📦 The new back cover is the original (MDG9) or a high-quality analogue with antenna tracks.
• 🎨 Double-sided tape or glue B-7000 — fixing.

Pay special attention to the choice of glue, because cheap superglue or low-quality Scotch will cause the lid to start to move away in a few weeks. B-7000 — It is elastic, water resistant and does not damage plastic parts during subsequent disassembly.

If you are buying a non-original cover, check for:

1. Antenna tracks for NFC and Wi-Fi.
2. The camera and fingerprint scanner holes (they must match the original).
3. Xiaomi logo – on fakes it is often blurred or displaced.

⚠️ Warning: Do not use the building dryer at maximum power! overheating above 90°C can melt plastic clips inside the case or damage the battery. Keep the hair dryer at a distance of 10-15 cm and evenly warm the lid in a circle.

Step 1: Remove the old cover

Start by turning off your smartphone and retrieving it. SIM-Then proceed with the algorithm:

Turn off your smartphone and take out the tray. SIM-map|

Warm up the hair dryer around the perimeter (2-3 minutes)|

Stick the suction cup closer to the lower edge (where the printing house is located)|

Carefully pull the suction cup upwards, creating a gap|

Insert a plastic shoulder blade into the resulting gap|

Swipe the blade along the edge, gradually separating the lid from the frame-->

The challenge is not to damage the fingerprint scanner plume that runs under the glass at the top of the device. If you feel resistance to jacking the lid, don't force it! Go back to the hairdryer or change the angle of the shoulder blade.

After the lid is removed, you will see:

• 📶 Antenna contacts – thin golden tracks around the perimeter.
• 🔋 Battery – it cannot be pierced or deformed!
• 📱 Medium frame with screws (they need to be unscrewed for complete disassembly).

If the lid is cracked but still held on to glue, paste it with tape before heating, this will prevent the fragments from breaking apart. For convenience, you can use an ultra-thin guitar mediator (0.38 mm) instead of a plastic shoulder blade.

⚠️ Warning: Don't pull the lid upwards, there may be glue fragments underneath that will pull the antenna tracks. Move slowly, warming up the dryer areas.

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If the lid doesn't lend itself, try heating it in two steps: first around the perimeter, then pointing it in the corners, which helps to smoothly soften the glue.

Step 2: Removing old glue and surface preparation

Once the lid is removed, there will be a layer of old glue on the frame, which must be completely removed, otherwise the new panel will fall unevenly.

Pay special attention to the area around the camera and the fingerprint scanner, and there are often microscopic glue fragments left over, which then lift the new lid, and check the surface at an angle, so you can see the contamination better.

If there are traces of corrosion on the frame (for example, from moisture), treat them. WD-40 And you dry it with a hair dryer, and ignoring that step will oxidize the antenna contacts and make the signal worse.

Step 3: Install a new cover

Before installing the new panel, check:

• 🔍 Coincidence of holes under the camera, scanner and microphone.
• 📏 The flatness of the edges - the cover should lie flush with the frame.
• 📡 Integrity of antenna tracks (attach an old cover for comparison).

For fixation, use one of the methods:

1. Double-sided tape is suitable for temporary repairs. Cut the strips around the perimeter, leaving the holes under the screws free.
2. Clay. B-7000 — apply a thin layer on the edge of the frame, avoiding hitting the antennas. Let dry for 5-7 minutes before installation.
3. Thermocleicle -- requires a special gun. Heat to 100.°C and apply point-on.

Installation algorithm:

1. Put the glue on the frame (not on the lid!).
2. Carefully apply the cover starting at the top edge (where the fingerprint scanner is).
3. Press the panel around the perimeter, avoiding excessive pressure on the center.
4. Secure the lid with tape at the edges and leave it under the press (for example, under a stack of books) for 1-2 hours.

⚠️ Warning: If the lid is "playing" when pressed, then there is not enough glue. Don't try to stick it on top, disassemble the device and apply the new layer according to the instructions.

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Check all functions after assembly: NFC, wireless charging (if supported), network signal quality, if something doesn't work, the problem is antenna contacts or improper lid installation.

Common Mistakes and How to Avoid Them

Even experienced craftsmen sometimes make mistakes when replacing the back cover with Xiaomi Mi. 9T. Here are the most common problems and ways to prevent them:

• 🔊 Scream of the lid after installation - the cause is usually uneven application of glue or dust. Solution: disassemble and repeat the procedure with cleaning.
• 📶 Bad signal, check the integrity of the antenna tracks on the new cover. If they're damaged, replace the panel.
• 🔋 Quick battery discharge - perhaps the battery or plume was deformed during assembly. Use plastic blades to avoid pressure.
• 💦 Moisture under the lid - if the smartphone is leaky, avoid using in wet conditions.Append an extra layer of sealant around the perimeter.

Another common problem is a broken fingerprint scanner, which happens when you hit or pinch the lid, to check if it's intact.

1. Remove the cover and inspect the plume for the presence of cracks.
2. Connect your smartphone to your PC and check if the scanner is detected in Device Manager (for Windows).
3. If the plume is damaged, it will have to be replaced - this is a separate procedure that requires soldering.

If the lid has been replaced, you may have forgotten to fasten the middle frame or you may have misplaced the heat sink. Disassemble the device and check the assembly.

Replacement of the display|

Disassembly of the hull|

Ringing plumes|

Diagnostics of malfunctions|Other-->

Checking of performance after repair

After assembly, you need to test all the functions of Xiaomi Mi 9T, You can use this checklist to replace the lid:

• 📞 Calls and mobile network -- check the signal quality in different places.
• 🌐 Wi-Fi and Bluetooth - connect to the network and check speed. Slowdowns may indicate damage to contacts.
• 🔓 Fingerprint scanner – add a new print and check the recognition speed.
• 📷 Camera: Take a picture on the main and front cameras. Blurring or artifacts indicate a displacement of the module.
• 🔋 Charging – connect the charger and check if there is overheating in the battery area.
• 🎵 Speakers and microphone – record a voice message and listen to it.

For a deep diagnosis, use the Xiaomi engineering menu:

1. Open the Phone app.
2. Enter ##4636##.
3. Go to Phone Information and check the status of the network, battery and sensors.

If you find a fault, don't try to get used to it. For example, a bad network signal over time can lead to loss of communication at a critical moment, and a faulty fingerprint scanner can lead to locking of the device, in which case it is better to re-disassemble the smartphone and eliminate the cause.

Cost of repair in the service center vs. self-replacement

Price of replacement of the back cover on Xiaomi Mi 9T Service centers vary depending on the region and type of spare part:

Self-repair is justified if:

• You have experience in disassembling equipment.
• You buy quality parts (e.g. a lid from a trusted supplier on AliExpress with a 98 rating%+).
• You are willing to spend time doing a good job.

Contacting the service is advisable if:

• Smartphone warranty (self-repair it cancels).
• You've never taken out smartphones.
• Not only the cover, but also the internal components (for example, the scanner plume) are damaged.

The average cost of tools for a one-time replacement (dryer, shoulder blades, glue) will be ~If you plan to repair the equipment further, this investment will pay off.

FAQ: Frequent questions about replacing the cover with Xiaomi Mi 9T