navigation blank screen HELP!!
 

i bought 2002 x5 4.6is and the navigation screen is blank but flickers the power light is on and i hear radio for 2 min then shuts off. in the back the navigation system 65-90-6-920-758 has no power light but the eject button does...it has NO cd in it maybe do i just need to put a cd in it? but still there no power light? hmmm i read many posts on here but confused!!!!!! and want radio!! please help newbie

also cd changer has no power are they connected? i check fuse in the back as well.if the computers gone can i replace it with another model?