Replace the faulty fingerprint sensor of your Mi 9

While fingerprint recognition may seem like a luxury, once you get used to it, you won't want to miss it. With this free guide, we'll show you how to repair a defective fingerprint sensor on your Xiaomi Mi 9 yourself.

Required tools

  • Flat Picks

    Flat Picks

    You need a very flat tool such as a flat pick to pry out parts that are glued in place.

    €5.00 at the iDoc store
  • For storing screws

    For storing screws

    We recommend storing your screws so you don’t mix up the various screws and small parts.

    €10.00 at the iDoc store
  • iPlastix Opening Tool

    iPlastix Opening Tool

    Do you want to open your smartphone or lever out large parts like the battery? Then the iPlastix with its large blade will help you. The practical assistant is made of flexible, especially sturdy plastic and lies comfortably in the hand. Thanks to its design, you can even get into smaller gaps, for example to lift the screen or to prevent it from sticking together again.

    €10.00 at the iDoc store
  • iSclack evo Opening Tool

    iSclack evo Opening Tool

    Opening your device can be a real test of patience, when the screen or back of your phone is glued very strong. With an iSclack evo, you can simplify the process. The pincer-like handle allows you to create a gap between the screen and the frame with minimal effort. At the same time, you have the other hand free to use a narrow tool such as a plectrum or the iFlex to enlarge the gap. The included cover foils allow you to use the iSclack evo even if the screen is splintered.

    €18.00 at the iDoc store
  • Tweezers

    Tweezers

    We recommend using tweezers to remove screws and various small parts from your device.

    €11.00 at the iDoc store
  • Steel Laboratory Spatula

    Steel Laboratory Spatula

    You need a flat and sturdy prying tool to disconnect glued parts.

    €4.00 at the iDoc store
  • Phillips PH00 screwdriver

    Phillips PH00 screwdriver

    You need the right screwdriver for removing PH00 screws.

    €12.00 at the iDoc store
Show all replacement parts for the Xiaomi Mi 9 

Passendes Werkzeug

Mit unserem Werkzeug gelingt dir die Reparatur.

for €40.00

Getting started with the repair of your Xiaomi Mi 9

If you get stuck or have questions, you can post a comment. We’d be happy to help.

15 steps
  1. Switching off the Xiaomi Mi 9

    Xiaomi Mi 9 - Switching off the Xiaomi Mi 9 01
    Xiaomi Mi 9 - Switching off the Xiaomi Mi 9 02
    Xiaomi Mi 9 - Switching off the Xiaomi Mi 9 03
    1. Turn off your device by holding down the power button until the “Power off” option appears.
    2. Use your finger to confirm that you want to shut down your device and wait until the screen goes blank.
  2. Removing the back cover

    1. The back cover’s heavily glued to the chassis. Heat the device evenly with hot air to soften the glue. A temperature of 60 - 80°C should be sufficient. As a rule of thumb, you should still be able to touch your device without it being uncomfortably hot.
    2. The easiest way to loosen the back cover is to use a flat and flexible tool such as the iPlastix or iFlex. You will also need several picks to unstick the back cover all around.
    3. Heat the spot where you start and place a flat tool between the back cover and the frame.
    4. Use a suction cup to lift the glass if you can't find a place to insert your tool.
    5. With the iSclack, you can easily lift the back cover and then use a flat tool to loosen the glue. Put both suction cups on the display and the backcover and press the lever of the tool together like a pair of pliers.

    The iPlastix is made of plastic, so it won't scratch the device. On the other hand, it's very soft and tricky to insert. The iFlex makes it easier to get into the gap between the glass and the frame because it's made of very thin, stable metal. But it also makes it easier to scratch the frame of your device.

    Be extra careful, the back cover can break very easily. If necessary, apply the heat several times and try again. Removing the back cover might take half an hour. Take a little more time and work carefully to make sure you don't break anything.

    1. Once the tool is inserted, stick a pick into the gap to keep it open. Then run the tool around the entire edge to gradually loosen the glue.
    2. Then heat the next part and insert the picks one by one.
    3. Once the rear glass is unglued, you can lift it off.

    The covers of the cameras remain in the device and are not permanently attached to the back cover. Loosen the adhesive there as well and take care not to damage the flex cable of the covers.

  3. Removing the midframe

    Xiaomi Mi 9 - Removing the midframe 01
    Xiaomi Mi 9 - Removing the midframe 02
    Xiaomi Mi 9 - Removing the midframe 03
    Xiaomi Mi 9 - Removing the midframe 04
    • 10 × 3,1 mm Phillips
    1. Loosen the Phillips screws that secure the cover. The wireless charging coil and NFC antenna are attached to the plastic cover.

    One or more screws may be covered with a sticker. Remove the stickers or pierce them with a screwdriver.

    1. The cover is hooked into the housing. Lever with a tool under the plastic frame and lift the frame upwards.
    2. Now you can remove the plastic cover together with the coil.
  4. Disconnecting the battery

    Xiaomi Mi 9 - Disconnecting the battery 01
    Xiaomi Mi 9 - Disconnecting the battery 02
    Xiaomi Mi 9 - Disconnecting the battery 03
    • Battery connector
    1. Using the spudger, carefully disconnect the battery contact from the motherboard.

    Always lever from a side where there are no small components on the motherboard. This avoids unintentional damage to capacitors or ICs.

  5. Removing the speaker

    Xiaomi Mi 9 - Removing the speaker 01
    Xiaomi Mi 9 - Removing the speaker 02
    Xiaomi Mi 9 - Removing the speaker 03
    Xiaomi Mi 9 - Removing the speaker 04
    Xiaomi Mi 9 - Removing the speaker 05
    Xiaomi Mi 9 - Removing the speaker 06
    • 1 × 2,6 mm Phillips
    • 4 × 3,1 mm Phillips
    • 2 × 3,8 mm Phillips
    • Antenna connector
    1. Loosen the Phillips screws that secure the speaker.
    2. One of the screws is covered with a sticker. Remove the sticker first or pierce it with your screwdriver.

    The screws have different lengths. Be careful not to mix them up. The easiest way to do this is with an iDoc magnet mat. You can place the screws on it the way they are in the device and due to the magnetic adhesion the screws will not get lost.

    1. Then lever one side of the speaker with a spudger until it comes out of the device.
    2. There is one antenna connected on the back of the speaker.
    3. Loosen the antenna with a pair of tweezers by inserting them under the cable and then carefully lever it.
  6. Information for repair guide

    Xiaomi Mi 9 - Information for repair guide 01
    Xiaomi Mi 9 - Information for repair guide 02

    In the following steps, the motherboard and battery are removed. However, this is not necessary for this repair.

  7. Removing the USB daughter board

    Xiaomi Mi 9 - Removing the USB daughter board 01
    Xiaomi Mi 9 - Removing the USB daughter board 02
    Xiaomi Mi 9 - Removing the USB daughter board 03
    Xiaomi Mi 9 - Removing the USB daughter board 04
    Xiaomi Mi 9 - Removing the USB daughter board 05
    Xiaomi Mi 9 - Removing the USB daughter board 06
    • 1 × 2,6 mm Phillips
    • Fingerprint connector
    • Antenna connector
    • USB connector

    The USB-C socket and a microphone are attached to the smaller circuit board at the bottom of the device. There are also antennas and the fingerprint sensor connected.

    1. First disconnect all connectors and the white antenna. Loosen the antenna by twisting the tweezers and then remove the antenna from its guide.
    2. Remove the single black screw that fixes the board.
    3. The board is glued into the device. Heat it evenly to loosen the adhesive more easily.
    4. Then you can lever it up a little on the upper side until you can remove it.



  8. The right tools for your repair

    With the right tools, you will succeed in any repair. In our store you will find a large selection of professional quality tools.
    VIEW NOW
  9. Removing the fingerprint sensor

    Xiaomi Mi 9 - Removing the fingerprint sensor 01
    Xiaomi Mi 9 - Removing the fingerprint sensor 02
    Xiaomi Mi 9 - Removing the fingerprint sensor 03
    Xiaomi Mi 9 - Removing the fingerprint sensor 04
    Xiaomi Mi 9 - Removing the fingerprint sensor 05

    The fingerprint sensor in the Xiaomi Mi 9 consists of a very small camera that is mounted directly under the screen.

    Be especially careful not to damage the sensitive flex cable when loosening the fingerprint sensor.

    1. Heat the flex cable evenly with hot air to make it easier to loosen.
    2. Then use a thin tool such as a steel spatula to carefully slide it under the cable and loosen it by levering it slightly.
    3. Also lever the camera module until it comes loose.
    4. When everything is loose, you can remove the fingerprint sensor from the device.
  10. Installing the fingerprint sensor

    Xiaomi Mi 9 - Installing the fingerprint sensor 01
    Xiaomi Mi 9 - Installing the fingerprint sensor 02
    Xiaomi Mi 9 - Installing the fingerprint sensor 03
    1. Reinsert the fingerprint sensor module into the device.
    2. Remove all adhesive around the camera opening if your replacement display has a new adhesive surface for the module.

    Make sure that there is no dust or dirt on the camera lens and inside the unit. This may cause the unlocking via fingerprint to not work correctly.

    1. Also position the flex cable underneath the camera correctly. A small nose in the device helps to position it there.
  11. Installing the USB board

    Xiaomi Mi 9 - Installing the USB board 01
    Xiaomi Mi 9 - Installing the USB board 02
    Xiaomi Mi 9 - Installing the USB board 03
    • 1 × 2,6 mm Phillips
    • Fingerprint connector
    • Antenna connector
    • USB connector
    1. Insert the board with the USB socket back into the device.

    Make sure that you do not pinch any cables under the board.

    1. Slide it down so that the jack and microphone are properly seated in the lower edge of the housing.
    2. Reconnect the two connectors and the white antenna cable.
    3. The easiest way to connect the antenna is to position it over its contact with a pair of tweezers and then press it down with a spudger. Also push the antenna into its guide on the board.
    4. Screw the USB board in place with the single Phillips screw.
  12. Installing the speaker

    Xiaomi Mi 9 - Installing the speaker 01
    Xiaomi Mi 9 - Installing the speaker 02
    Xiaomi Mi 9 - Installing the speaker 03
    • Antenna connector
    • 1 × 2,6 mm Phillips
    • 4 × 3,1 mm Phillips
    • 2 × 3,8 mm Phillips

    At the back of the loudspeaker an antenna has to be connected first.

    1. Put the speaker in position and connect the black antenna cable with a pair of tweezers and a spudger.
    2. Then reinsert the speaker over the USB port, press it tight and screw it into place.



    Make sure it sits flush at the bottom of the device.

  13. Connecting the battery

    Xiaomi Mi 9 - Connecting the battery 01
    Xiaomi Mi 9 - Connecting the battery 02
    Xiaomi Mi 9 - Connecting the battery 03
    • Battery Connector

    Reconnect the battery.

    1. Position the connector over its socket on the main board and press it down carefully.
  14. Installing the midframe

    Xiaomi Mi 9 - Installing the midframe 01
    Xiaomi Mi 9 - Installing the midframe 02
    Xiaomi Mi 9 - Installing the midframe 03
    • 10 × 3,1 mm Phillips
    1. Put the cover with the antenna back in the enclosure after hooking it onto the top of the enclosure.
    2. Then press the cover with your fingers until it clicks gently into place.
    3. Fasten the phillips screws.
  15. Testing the Xiaomi Mi 9

    Xiaomi Mi 9 - Testing the Xiaomi Mi 9 01
    Xiaomi Mi 9 - Testing the Xiaomi Mi 9 02
    Xiaomi Mi 9 - Testing the Xiaomi Mi 9 03
    Xiaomi Mi 9 - Testing the Xiaomi Mi 9 04
    1. Turn on your device and test it before you finally close it.
    2. Drag any app across the entire screen. Drag the app once around the entire border and then in a zigzag across the screen. The app should always follow your finger.
    3. Then test the display brightness by dragging the brightness slider to minimum and maximum.

    Test especially all functions of the part you replaced.

  16. Attaching the backcover

    Xiaomi Mi 9 - Attaching the backcover 01
    Xiaomi Mi 9 - Attaching the backcover 02
    Xiaomi Mi 9 - Attaching the backcover 03
    Xiaomi Mi 9 - Attaching the backcover 04
    Xiaomi Mi 9 - Attaching the backcover 05
    1. Check the adhesive on the edges of the back cover. If it's mostly intact, you can use it again and don't need any new glue.
    2. Make sure that the adhesive lies flat and does not wrinkle. If this is the case, warm it up a little and correct it with tweezers.

    Also check the adhesive around the camera cover and correct it if necessary.


    1. If the adhesive frame is too loose or does not stick properly, use new adhesive.
    2. To do this, first remove all old adhesive residues from the back cover. Use hot air again to loosen the glue more easily.
    3. Then apply the new adhesive frame or thin double-sided tape to reglue the backcover.
    4. Position the back cover over the device and press it down when it is exactly in the center.
    5. Heat the glue one last time and press the backcover on. You can weigh the device down with books or use clamps to compress the glue as long as it cools down (about 10-20min).
Ø 5 (1 Ratings)

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