LCD panel? Should go away after a while, just need that spot to return to its "normal state" which it shud do after alot of colors have been shown on that area
If not id get a new one if ur warranty is still active
should go away over time, guessing its just a problem with ghost image / image persistence due to it being idle for 2long. i have heard running a video with flashing white / black might reduce the time it takes for it to disappear (reset to its original state) , but i haven't had this problem myself so cant really confirm
try running this for some minutes, not sure if it will help though, but worth a shot