There are several ways in which the Samsung Galaxy S6 lock screen can be unlocked. One of them is the fingerprint. Therefore the finger is placed on the home button. The sensor detects the structure of your finger and the fingerprint and then unlocks your smartphone. That is the theory.
Now it may be that the fingerprint is not recognized correctly by your Samsung Galaxy S6. Even after repeated placement of the finger on the fingerprint sensor the finger is identified as incorrect, which then obtains the input of a pin, which has also been determined in advance. Should this be the case with the unblocking "fingerprint" even with your Samsung Galaxy S6, then please consider the following tips:
1. The fingerprint scanner can recognize your fingerprint very difficult when it is moist, sticky etc.. Especially when your hands are wet, the sensor has problems to recognize the fingerprint. Clean the sensor briefly before placing the finger on it.
2. Often, temporary system files that are out of date lead to problems on your Android device. That is why we recommend to you perform a Wipe Cache partition. Thus, the old system files of Android will be deleted, which may lead to a positive result with the fingerprint. The Wipe Cache works like that.
3. Should that not have helped, please check the opportunity to perform a factory reset. This will be reset the smartphone to factory settings. This can lead to a solution of the fingerprint problem. The factory reset can be carried out as follows.
4. Should the advice not helped, then we recommend you to make use of the warranty of your Samsung Galaxy S6. Because then the sensor is most likely broken for detecting the fingerprint.