Disassembly of the thermometer Xiaomi: step-by-step guide with photos and expert advice

Xiaomi thermometers are some of the most popular smart home gadgets due to their accuracy, compactness and integration with the Mi Home ecosystem. However, over time, even such a simple device may require cleaning, battery replacement or repair after a fall. It’s not as difficult to disassemble the Xiaomi thermometer as it seems, but there are nuances here, from the type of case (glue or latch) to the location of hidden mounts that are easy to break if handled carelessly.

In this article, you will find step-by-step instructions for different models, from the classic Mi Thermometer to the Smartmi Air Detector, as well as a list of necessary tools, photos of internal components and tips for reverse assembly. We will also tell you how to avoid typical errors that lead to sensor failure or loss of leakage. If your thermometer stopped syncing with your smartphone, shows incorrect data or simply needs preventive cleaning, this guide will help you cope without going to the service center.

⚠️ Important: Disassembly of Xiaomi device may void warranty. If your thermometer is still warranty service, first contact the official service. Also remember that improper disassembly can damage the humidity sensor or loss of calibration, which will make the reading inaccurate.

What Xiaomi Thermometers Can Be Disassembled By Yourself

Not all Xiaomi thermometers are disassemblable at home, for example, some Mijia series models have ultrasonic body welding that cannot be detached without special equipment. However, most popular devices are disassembled using improvised tools. Here is a list of models for which this instruction will suit:

• 📱 Xiaomi Mi Thermometer (LYWSD02, LYWSD03MMC) — classic LCD-screen.
• 🌡️ Xiaomi Smartmi Air Detector (PM2.5, temperature, humidity).
• 🏠 Xiaomi Mijia Bluetooth Temperature and Humidity Sensor 2 (round case).
• 🔋 Xiaomi ClearGrass Thermometer (with a replaceable battery) CR2032).

If your model is not on the list, check the type of attachment of the case. To do this, carefully swipe the nail along the seam between the top and bottom: if you feel a gap or click, it is likely the case on the latches. If the seam is perfectly smooth, there is a high risk that the body is glued or welded.

💡 Tip: Before disassembling, take a picture of the device from all sides, which will help to properly assemble it back, especially if there are small parts inside (for example, gaskets for leakproofness).

Tools and workplace preparation required

Xiaomi doesn’t need professional tools to disassemble the thermometer, but without some tools, you risk damaging the body or internal components.

• 🔧 Plastic mediator (or guitar mediator) – to disconnect latches.
• 🔪 Thin screwdriver (cross or flat, depending on the screws).
• 🧲 Magnetic screwdriver or tweezers - so as not to lose small screws.
• 📸 Lupus or macro lens of the smartphone – to inspect small details.
• 🧴 Isopropyl alcohol (70%+) — clean-up.
• 🧼 Cotton swabs - to remove dust inside the case.

Also, make sure you have a clean, well-lit workplace, and make sure you cover your desk with white paper or cloth, so you don't lose any small details and notice the dust inside your device, and if you're disassembling a thermometer with a humidity sensor, like a Smartmi Air Detector, avoid high humidity spaces, which can distort calibration after assembly.

⚠️ Warning: Don't use metal tools to unplug the latches! They can leave scratches on plastic or damage the PCB. If you don't have a plastic mediator on hand, you can use an old bank card or even a dense cellophane (for example, from packing gadgets).

How to disassemble the Xiaomi Mi Thermometer (LYWSD02/03)

Models. LYWSD02 and LYWSD03MMC They're similarly designed, so the instructions are good for both. LYWSD03MMC It uses a built-in battery and LYWSD02 — removable CR2032. Let's take this process as an example. LYWSD02:

1. Remove the back cover. Turn the thermometer down. At the bottom you'll see a screwdriver slot (some models have it hidden under the sticker) gently slap the lid with a plastic mediator starting from this groove. Go around, flipping the mounts one by one, 4 to 6 of them, depending on the version of the device.
2. Battery extraction. If your model has a removable battery, gently tuck it in with a screwdriver. Notice the polarity (usually marked on the board). In LYWSD03MMC, instead of a battery, you'll see a lithium battery soldered to the board -- it's best not to touch it unnecessarily.
3. Disconnect the board. Once you remove the lid, you'll see a circuit board attached to 2-3 screws (cross or flat) unscrew them and raise the board carefully. Be careful that sensor wires (in models with an external probe) may be soldered to it.
4. You'll find sensor access on the board: 🌡️ Temperature sensor (usually marked) HTU21D or SHT30). 💧 Humidity sensor (often combined with temperature). 📶 Bluetooth module (to communicate with a smartphone).

🔍 What to do if the body does not yield?

If the latches don't snap, try to heat the body with a hair dryer (temperature no higher than 50°C) to make the plastic more elastic. Don't use excessive force, or you'll break the mounts.

⚠️ Note: If you are disassembling a thermometer to replace a battery, use only original elements. CR2032 From proven brands (e.g. Panasonic or Maxell), cheap ones can leak and damage the board.

Smartmi Air Detector Disassembly: Features and Risks

The Smartmi Air Detector is more sophisticated than the classic thermometer, as it features an PM2.5 sensor and a fan to take air intake, and it requires more care to disassemble, but is possible at home.

Main stages:

1. Remove the top lattice. The lattice is attached to 4 latches hidden under the rubber legs. Carefully tuck the legs (they are glued) and remove the lattice. Under it you will see a fan and a particle sensor.
2. Fan disconnect. Fan plugged into board with 3-wire connector. Gently disconnect it, don't pull the wires! If you want to clean the blades, use a soft brush or compressed air.
3. Access to the main board. The board is held by 3 screws under the cross screwdriver. Once unscrewed, you can raise the board, but be careful - it is soldered with a PM2.5 sensor (usually marked PMS5003 or SDS011).

If the thermometer is not activated:

1. Check the polarity of the battery (even if it is inserted correctly, the contacts may have oxidized).
2. Check the fuse on the board (if any) - it could burn out when the voltage jumps.
3. Check the integrity of the tracks under the magnifying glass, and sometimes after a fall, microcracks appear.

💡 Tip: If the humidity sensor shows an inflated value after cleaning (for example, 99% at normal room humidity), leave the thermometer for a day in a dry place with silica gel (packages from shoeboxes.

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If the thermometer stops syncing with the Mi Home after assembly, try resetting it to factory settings. To do this, hold the reset button (usually hidden under a small hole on the back) for 10 seconds until the indicator blinks 3 times.

Reverse Assembly: How to Avoid Mistakes

Getting Xiaomi’s thermometer back together is often harder than making sense of it.

1. Checking the sealing gums. Most models have a silicone gasket between the case and the board to keep it tight. Make sure it lies flat and not twisted. If the gasket is torn, replace it (you can cut it out of thin silicone).
2. Fixing the board. The screws need to be twisted cross-to-cross so that the board sits flat. Don't drag them over, which can lead to board warping and loss of contact.
3. Test before final assembly. After the board is installed, but before the case closes, insert the battery and check if the device is switching on. If not, take it apart again and check the contacts.
4. Closing the case. Start on the opposite side of the latches, gently pressing the lid until the click. If the case does not close until the end, check if a foreign object (such as a strip strip strip) has entered.

⚠️ Warning: If the thermometer shows incorrect data after assembly (for example, temperature at 5-10).°C above the real one, most likely, the sensor has shifted or dusted onto the sensitive element. Take the device apart again and make sure that the sensor is pressed tightly against the hole in the housing.

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The most common assembly error is the incorrect installation of the sealing gasket, which leads to dust entering the housing and sensor failures.

Frequent problems after disassembly and their solution

Even if you carefully disassemble and assemble the Xiaomi thermometer, you may have problems. Here are the typical symptoms and ways to treat them:

If the thermometer never worked after all the manipulations, it could be the firmware problem, LYWSD03MMC) can be re-flashed UART-It requires soldering iron skills and knowledge of commands for the terminal.

🔧 For experienced users:

If you are confident in your abilities, you can try updating the firmware through a USB-TTL adapter. Connect to the TX, RX, GND and 3.3V contacts on the board, then use the command:

esptool.py -p /dev/ttyUSB0 write_flash 0x0 firmware.bin

You can download the original firmware on the 4PDA or GitHub forums (see the device model).

FAQ: Answers to Frequent Questions