Brand new S6. Not the Edge model. UK model. First time switched on, I set it all up with my long time Google account, it started a large Android update, switched off, back on. The usual thing they do. Now I found I swipe the unlock screen, I get a black screen. I took my sim out and get a message saying sim removed. I can't switch it off. The menu comes up with power off, etc the screen is unresponsive. I purchased it off EBay. Best to send it back? I feel guilty. I haven't dropped it just to be clear. The volume button works. The pull down menu with WiFi, Bluetooth, doesn't.. I can't even factory reset it. Advice please. Thanks