When I power up my Roku 4, sound and picture are clear on the start-up. Then when the channel menu page comes up the picture scrambles. A problem started recently where the text in certain apps like Disney+ and Netflix began showing up as dashes instead of letters and numbers. Then two days ago the Roku stated on its own and the channel menu picture has been scrambled ever since. Tried unplugging and also tried home x 5, up once, rewind twice, forward twice. Did not work. Now looking for hard reset button on the Roku itself. Is that the button with the plus sign on top of the unit? I know pushing that button one way causes the remote to beep. What does the other part of that button do? Cant find a pin hole on back or bottom of unit for a hard reset. Any suggestions would be welcome. Thanks.