Is your device running on the latest firmware? To check this, go to Settings > About Device > Software Update > Check for updates. The Galaxy S3 should be running on 4.3 Jelly Bean.
If the software is fully up to date, I recommend performing a factory data reset on your device. You can do this by following these steps:
Settings - Back up and reset - Factory data reset - Reset device - Erase everything.
Performing a factory data reset will erase all data from your device. I advise that you back up your data on Samsung KIES. Please see the link below to find all of the information and tutorials on Samsung KIES:
If the factory data reset does not rectify the screen mirroring error, I advise taking your Galaxy S3 to your nearest service centre. Please visit the link below which will aid you in locating it:
I hope this helps.
answered 2 months, 2 weeks ago
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