Nextbase dvd

Question

hi i have a 1-yr old nextbase portable dvd. it is in good condition since we rarely use it anyway. then when i tried to play a dvd movie using the ac/dc adapter the screen went black. the audio was ok, but only shadows were visible on the screen. i tried using the rechargable battery instead of the adapter, and everything went ok. the picture was clear. everytime i try using the adapter, still no picture. is it an lcd problem? please help. thanks