apple tv stuck on black screen with a white round shape flashing at the righ-hand side of the screen every 2 seconds

Seems to be locked out of my Apple TV 4k. Apple TV responds to the remote alright as it comes out of its screen save mode but only to show on a black screen and white roundish shape flashing on the RHS of the screen every 2 seconds.. Pressing the menu button shows a white box with "English" on it and scrolling down shows different languages (only one white box is shown at any time and the rest of the screen is black). Selecting the English box makes it show the apple logo and an update bar below it brief then it goes back to the black screen again. Leaving it alone long enough makes it revert to the screen saver video. Has anyone experienced this? I though it might just be updating itself but its been over 7 hours now and I still cant fix it. I would really appreciate some help with this..