got a used unit. has no power cord but has both the battery and a car cigerette power cord adapter. went to test the u8nit with the car power adapter and the dvd played but was poor quality. took the movie out to try another dvd and lost the screen (nothing) however the indicators on the unit were showing power because of the indication lights. on further testing, i disconnected the battery and ran the unit with the car cig. adapter alone. this time no power at all to the unit. what could possibly be causing this problem. do you need a known good battery to make the car power adapter to work? please help me solve this problem. thanks. terrymalo45@hotmail.com 360-691-3172