aibi , i'm not sure what can be done about it.
Since you bought it 6months ago, it should be running off the v3.5.xx series. So try a firmware extraction, repair, and re-flash.
Extraction & repair guide here
http://www.mympxplayer.org/how-to-ex...tool-vt66.html
Re-flash guide here
http://www.mympxplayer.org/how-to-up...ayer-vt46.html
If the problem still persists, most probably it'll be hardware problems. Maybe some component is failing, and the screen does not stay lighted as supposed to.