This is IR and since you detected it late, it will take some days to go. Burn in is when you can see the IR even when another channel is on - when those phosphors are burnt in and do not change color.
Everytime before you shut off, switch to TV mode and keep the black and white blinking dots on for 2-3 minutes (for your case... otherwise 20-30 seconds is fine). Since you can still see the IR after scrollbars, it may take a few days for it to fully go. You can also use the burn in white scroller - note that it uses 100% bright scroller, so I am not sure how good it is to be used for long duration.
I would also suggest you to watch SD content full screen to avoid the side bars. That way, your channel/DTH logo that has caused IR will also be shifted towards the side and help you ease out of the IR already caused.