It sounds like you might be experiencing an issue related to the touch calibration or screen alignment after replacing the display on your ***Samsung A21***. Here’s a detailed troubleshooting guide to help address this issue:
=== 1. ***Check Screen Installation and Connections*** ===
* ***Ensure Proper Installation***: Double-check that the display is properly seated and that all connectors are securely attached. A loose or improperly connected display could lead to touch input issues.
* ***Inspect the Display Cable***: Ensure that the display cable and digitizer cable are not damaged and are connected correctly. Look for any kinks or signs of damage.
=== 2. ***Touch Calibration*** ===
* ***Calibrate the Touchscreen***: Some phones allow you to calibrate the touchscreen. While Samsung phones generally don’t have a built-in calibration tool, you can use third-party apps from the Google Play Store that help calibrate touchscreens.
** ***Download a Calibration App***: Search for "touchscreen calibration" apps on the Google Play Store and follow the instructions provided.
=== 3. ***Check for Screen Protector Issues*** ===
* ***Remove Screen Protector***: If you have a screen protector installed, it might interfere with touch inputs. Try removing the screen protector to see if the issue persists.
=== 4. ***Software Update and Settings*** ===
* ***Update Software***: Ensure your phone’s software is up to date. Go to ***Settings*** > ***Software update*** to check for updates.
* ***Safe Mode***: Booting into safe mode can help determine if a third-party app is causing the issue. To enter safe mode:
** Press and hold the ***Power button*** until the power off menu appears.
** Tap and hold ***Power off*** until you see the Safe Mode prompt, then tap ***Safe Mode***.
** Check if the issue persists in safe mode.
=== 5. ***Touchscreen Test*** ===
* ***Run Diagnostic Test***: Some Samsung phones have built-in diagnostic tools that can test the touchscreen.
** Dial ``***''#0''#***`` on your phone’s dialer to access the diagnostic menu.
** Tap on ***Touch*** to test the touchscreen. This can help identify if there are dead zones or touch issues.
=== 6. ***Check for Interference*** ===
* ***Check for Interference***: Ensure that no external factors are affecting the touchscreen. For example, magnetic cases or accessories might interfere with touch sensitivity.
=== 7. ***Factory Reset*** ===
* ***Backup Data***: Before proceeding with a factory reset, make sure to back up your data.
* ***Perform Factory Reset***: If none of the above steps resolve the issue, consider performing a factory reset:
** Go to ***Settings*** > ***General Management*** > ***Reset*** > ***Factory data reset***.
** Follow the on-screen instructions to reset your phone. This will erase all data on the device, so ensure your data is backed up.
=== 8. ***Professional Repair*** ===
* ***Seek Professional Help***: If the problem persists, it may be best to consult a professional repair technician. They can recheck the installation and potentially identify any hardware issues.
By following these steps, you should be able to diagnose and potentially fix the touch input issue on your Samsung A21. If you need further assistance or have specific questions about any of these steps, feel free to ask!