Audio Systems: Flip-down rear seat entertainment in Chevy Suburban, 2003 chevy suburban, chevy suburban

Question
I need assistance dropping the factory installed Panasonic flip down rear seat entertainment unit from the "ceiling" of my 2003 Chevy Suburban.  I have loosened four 10mm captive bolts, 2 just aft of the screen and 2 accessible through a flip down access panel just aft of the control head.  The unit seems slighly loose but there must be something I am missing because it won't drop from the ceiling.  Any help geatly appreciated.  My grandsons are going nuts without the thing working.
Thank you

Answer
I highly doubt this is a factory system with Panasonic on it. GM systems either say nothing, or Delphi. Anyhow, someone installed this after the fact, and you will just have to do some detective work. Perhaps there is a screw drilled into the mounting bracket, but hidden unless you take it all apart.