POCO F3 Power Button Flex Replacement Guide | Fingerprint Repair – Xiaomi Mi 11X/11i | Redmi K40

Hi everyone, welcome back to Geardo.
Today, we will show you how to replace the power button and fingerprint sensor flex cable on the Poco F3, also known as the Xiaomi Mi 11X and Redmi K40.

If your power button is not responding or the fingerprint sensor is not detecting properly, replacing this flex cable will usually fix both issues. This guide is beginner-friendly—just follow the steps carefully.

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Repair Overview

• Device Type: Smartphone
• Repair Type: Power Button & Fingerprint Flex Replacement

Repair Difficulty: ★★★☆☆ (Moderate)

• Estimated Time: 40–60 minutes

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Reasons for Repair

• Power button not working or stuck
• Fingerprint sensor not detecting
• Intermittent power button response
• Physical damage to button flex

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Before You Begin

Compatibility and Model Numbers

• Redmi K40 Series ( Redmi K40 / K40 Pro / K40 Pro Plus) 
• Xiaomi 11x / 11i Series
• Poco F3 Series

Model Numbers : M2012K11AG, M2012K11AC, M2012K11C, M2012K11AI, M2012K11I

This guide is based on the Redmi K40, which shares identical design with the Poco F3 and Xiaomi Mi 11X / Xiaomi Mi 11i. These are rebranded regional models, but always watch for minor internal differences during the repair.

Tools Required

• Mobile phone heating pad or hairdryer/heat gun
• Plastic pry tool / card pry
• Suction cups
• Phillips #00/#000 screwdrivers
• Torx (T2/T3/T4) screwdrivers
• Flathead screwdriver
• Tweezers (for connectors)
• B7000 glue or double-sided adhesive (for back cover)
• Rubber bands or bonding clips to secure the back cover

How to Find Tools and Parts

• Heating pad – https://amzn.to/3H0tHzJ
• Portable Heat Gun – https://amzn.to/4mszih1
• Clamps https://amzn.to/3GYJT4w
• STREBITO 142 Piece Repair Tool Kit https://amzn.to/3UO1jUx
• Glue | Adhesive https://amzn.to/46exVxe
• Compatible Parts –
  • Battery – https://amzn.to/4t0Aw6W
  • Screen – https://amzn.to/48hkKfR
  • Other Parts – https://amzn.to/4cF5E69
• Silicone Work Repair Mat https://amzn.to/45Emz5l

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 Protect Your Phone 

• Best Premium Case https://amzn.to/4cF5E69 
• Screen Protector https://amzn.to/423YP86

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Important Note (Compatibility)

This guide is based on the Redmi K40, which shares the same internal design as the Poco F3 and Xiaomi Mi 11X. These are rebranded regional models, so the process is the same.

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Step-by-Step Power Button & Fingerprint Repair

Step 1: Power Off & Remove SIM Tray

Turn off the device and remove the SIM tray.

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Step 2: Open the Device & Remove Back Cover

• Apply gentle heat around the edges
• Use a suction cup to create a gap
• Insert a plastic pry tool/card
• Carefully cut the adhesive and remove the back cover

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Step 3: Remove the Board Frame

• Undo 11 screws
• Disconnect the flash connector
• Lift and remove the board frame

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Step 4: Remove the Battery

• Disconnect the battery connector
• Pull adhesive strips from the sides
• Gently lift and remove the battery

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Step 5: Remove the Faulty Power Button & Fingerprint Flex

• Apply gentle heat along the side frame where the flex is attached
• Carefully peel the flex cable from the frame
• Remove the fingerprint/power button through the side opening
• Take out any brackets or rubber supports if present

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Step 6: Install the New Power Button & Fingerprint Flex

• Insert the new power/fingerprint button through the side opening
• Align the flex cable along the frame
• Press and secure it into place
• Reinstall any brackets or rubber holders
• Ensure proper alignment with external buttons

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Step 7: Reinstall the Battery

• Place the battery back into position
• Secure adhesive
• Reconnect the battery connector

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Step 8: Reinstall the Board Frame

• Place the frame back
• Secure with 11 screws
• Reconnect the flash connector

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Step 9: Test Before Closing

Power on the device and check:

• Power button functionality
• Fingerprint sensor response

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Step 10: Close the Device

• Apply adhesive if needed
• Reinstall the back cover
• Press firmly around edges
• Use clips or rubber bands for proper bonding

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FAQs

Q1: Why is my fingerprint sensor not working?

It may be due to a damaged flex cable or worn-out button assembly.

Q2: Can I replace only the power button?

In most cases, the power button and fingerprint sensor come as one combined flex cable.

Q3: Is this repair beginner-friendly?

Yes, but requires careful handling and heating.

Q4: Do I need to remove the logic board?

No, this repair can be done without removing the logic board.

Q5: Will this fix power button issues completely?

Yes, if the issue is hardware-related.

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Troubleshooting (After The Repair)

Q1: Power button still not working

• Check flex cable alignment
• Ensure connector is properly seated

Q2: Fingerprint not detecting

• Recheck placement of fingerprint sensor
• Clean sensor surface

Q3: Phone not turning on

• Verify battery connection
• Charge device and try again

Q4: Buttons feel loose

• Ensure brackets and rubber supports are installed correctly

Q5: Back cover not sealing properly

• Use new adhesive or B7000 glue
• Apply pressure with clips

Related Guide

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