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Besides from finger print, it should also ask for a password (backup PIN or password). So enter that backup print to unlock it.
If you don't remember it, then enter some incorrect password ***** when you enter wrong password ***** multiple times continuously, it should ask for the Gmail account associated with it. So use that Gmail account to reset the password ***** get back to your phone.
If that didn't work,then we can try to unlock it directly from Samsung Find My Mobile service. This will only work if you have the Find My Mobile option enabled on it (i.e if registered a Samsung account on it). Go to this website --> https://findmymobile.samsung.com/
Login to your Samsung account. Select your device on there. Click More on the right side under Ring My Device, Lock My Device etc. Then click Unlock Device and when you do that, your screen will be unlocked. This will only work if Samsung account is installed on phone and if it is connected to internet.
If that didn't work, then the only option to get in to the phone is factory-reset it. There is no other way to override the password/finger print screen if the Gmail or Samsung website option didn't work. Factory reset will erase everything from it and return it to new (like Out of Box). This is how they designed the device. Follow the steps below to factory reset it (make sure you follow the steps below exactly or it will not work);
Turn off the phone
Press and hold down Volume Up, Home and Power buttons at the same time.
When it turns on,release the Power button but continue holding down Volume Up and Home button.
Android system recovery will be loaded now
Select wipe data/factory reset.(Volume buttons to go up or down, select with Power button)
Select Yes — delete all user data.(Volume buttons to go up or down, select with Power button)
Then select reboot system now(Volume buttons to go up or down, select with Power button)
That should factory reset the phone. After factory reset, you need to setup the phone again (like anew phone). I'm sorry, but there is no way to avoid the reset if the above doesn't work. Even if you take it to Samsung store, they will not be able to unlock it. These devices are very secure.
If you have any difficulty on following the steps above, please let me know and I will walk you through it.