LG K20 plus: in Secure start-up with pin pattern with message no screenshot when phone is encrypted?

[Android Central Question]

My LG K20 Plus: Phone has pattern pin I didn't set, and its in Secure start-up mold. It also say that you can't take a screen shot when the phone is encrypted. I tried to factory reset it. >Power & Valume Down button but not working.
Can anyone HELP me Please.
Faithful Google game player.
MsMattbbm.