My S6 locked in an unfamiliar screen?

A

AC Question

My S6 locked in an unfamiliar screen

I have a S6 bought second hand and I tried to find the serial number but I have come to a blue screen showing the following in the top left hand corner

ODIN MODE
PRODUCT NAME: SM-G920F
CURRENT BINARY: Samsung Official
SYSTEM STATUS: Official
REACTIVATION LOCK: Off
Secured Download: Enabled
KNOX WARRENTY VOID: 0 (0x0000)
AP SWREV: B:3 K:3 S:2

In the middle of the screen is a box containing an down pointing arrow and below this it states "Downloading" and below that "Do not turn off target"

The phone is locked and unresponsive.

Please help.