I wrote a lengthier response, but I may have timed out... In a nutshell, I was in the same boat: my fingerprint scan failed 5 times and I forgot my backup password. I tried the Device Manager approach, but it wouldn't reset the password for a phone that was already locked. I ended up at findmymobile.samsung.com. I found the "Unlock phone" feature, and it worked! The caveat is I think you have to have a Samsung account already for the locked phone. Not sure on that, because I didn't have to create one after I was locked out; I did it a month or so ago (can't remember why exactly, but obviously glad I did now). Otherwise, factory reset I'm afraid. And if you haven't backed up your phone manually or automatically via your cellular service provider's cloud (turned out I had a backup in Verizon's cloud that I could have restored from if I had to), you're out of luck. Hope this helped.