I registered just to answer this question, and make it easyer for other people ( I'm also copy-pasting it to other sites I was searching before I fould the solution)
Guys I spent around 15 hours trying to unlock my samsung galaxy s6, and found a solution. You're wellcome because you need google acc+dont need a connection for this to work (worst case scenario).
It didnt recongnize my fingerprints, and my backup password didnt work. I couldnt sign in to my google account since my wifi and mobile data was turned off before the device locked.
This is the solution i found AFTER 15 hours of this madness, you need to be quick:
1) enter wrong backup password 5 times
2) wait 30 secounds countdown
3) enter wrong backup password 5 times
4) wait 30 secounds countdown
5) select sign in with google account
6) enter google account credentials (DONT SIGN IN YET)
7) hold 'wake up button' (home button)
8) press emergency mode and go thru with aggreeing to all it asks you to
9) press TURN ON, and after that press 'sign in' with your google account (where step 6 left off)
If you were quick enough, you will enter emergency mode and you will pass the lock screen, now quit the emergency mode the same way and change your backup password, and write it down this time so this doesnt happen again. You are wellcome.