I've pressed the POWER and VOL UP and VOL DOWN buttons and then got the screen with the android then I pressed recovery mode after that I saw the android with a ! sign in the red triangle. I tried pressing the POWER button and the VOL UP button but then it puts me on the downloading... do not turn off target screen. I want to hard reset my Nexus 10 but I don't know what to do and google support didn't help at all with the problem. What am I doing wrong?