2005 Navigator factory overhead prob

i recently installed a n-2 and visor screen in a 2005 lincoln navigator with the foctory overhead with built in dvd and after the instalation the overhead isn't  working and was wondering if anyone knows of what it is haven't had a change to look at it yet but guessing it was tied in with the factory radio

thanks

The overhead is powered by you factory head unit. once you remove it there in no longer any power going to it. I had the same problem after putting in an eclipse avn5435 in my navigator. i have my overhead dvd player hooked up to run independantly. it is powered up and only can be heard through the headphone jacks from the center console. this way i can still listen to music, watch a movie, or play games in the front while the people in the back can watch what they want. i think this is the only way to run it because the factory head unit controls it. to me this is the best way to run it anyway.

here's what was done:

the shop that installed my head unit and they figured it out. no charge. first they located the power wire and powered it up. not sure which wire this was but i thinks its in the same haress that goes to  the head unit. after powering it up we could watch dvd's on the screen but with no sound. for the sound they found the siginal coming from the red and black wires at the back of the dvd player. they tapped it and touched the leads to the head phone jack. you could hear the audio but it was not loud enough. they converted the red and black wires into rca's and installed a line booster to make it louder. the line booster is very small and was tucked into the case of the overhead. they ran the rca's from the dvd player to the center console's head phone jacks and hard wired it. now the audio is very loud through my head phones. i needed head phones with volume control because without that it would play at full blast. the people that ride in the back say it feels like being in an airplane.