Did you just get the car or did it suddenly stop working? It definaltey sounds like a power issue. Either it is not getting power or it is broken and can't get any power. For those who DIY install the overhead DVD, is there a dedicate fuse?
Whatever you do, do NOT get a replacment, it's not worth it. If you have an Android or IOS phone/pad, I HIGHLY recommend the Samsung SE-208BW for ~$50 and a cheapo AC/DC converter. The Samsung is a wifi enabled DVD (content on a USB drive too!) player meaning it sends audio/video out to you phone/pad via wifi. Not like the typical wifi enabled players, which really mean you access Netflix, etc. through it. Get a tech savvy family/friend who knows a little bit about network setup to get it going. Set it up once and you are done. It is well worth it.