Samsung S6 edge asking for password after reboot

[Android Central Question]

After battery drains out, my phone is now asking me for some password after i start it up. I used fingerprint as unlock option, but now i cant do anything before entering password. I already tried 2 passwords which were in my head but not working. Problem is that everytime i enter password, and its wrong, it takes me more time to wait until next try.
Some help? I already called the service but they said that only service can save the device with completely resetting device.

Would appriciate any hint or help.
Thank you

 

[Mooncatt]

When you originally set up the fingerprint to unlock the phone, you would've been required to setup a password (or confirm an existing one) as a backup unlock option in case you could no longer use the fingerprint scanner. That is the password you need to enter when rebooting your phone. All phones are like this, both in requiring a backup password/pin and requiring its use after a reboot.

If you do not remember that, then the service center is correct that only a factory reset would remove the password. It also means needing to remember your Google account email and password you used to sign in on the phone when you set it up again to get past the factory reset protection check. If you don't know that, then you're out of luck.