locohasa, thanks for your reply. There is no "left button on the top". There is only the round "" button on my front screen. The "On/Off" slider is on the side. I did not see any other button. There is something on the side which is similar to the button that I use to turn up/down the volume on my phone. I tried that too. I am attaching the picture of my unit. Can you help me locate this button? Thanks again.