My son tried entering my knock code in my phone so many times it locked me out of using the fingerprint too. And i just changed the code from a pattern to a knock code.
I don't know why it wont let me use the fingerprint....it just says "unable to use fingerprint". My screen has four boxes for the knock code and thats it. It let's me try the code but I haven't got in yet. I've tried 50+ times. Lbvs.