Thursday
Thursday - last edited Thursday
Thursday
Thursday
Friday
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First, run software tests on your phone. If it works in those tests, it is a software problem and can be fixed by resetting the settings.
If there is an error there too or the vibration does not work, you should connect the phone to the computer and test it with the phone's testing software. If the computer does not show any errors, the phone should be factory reset. If there is an error and it does not work, it is a hardware problem and the vibration should be replaced.