Those 2 pins are not connected the the ribbon. It supplies power to the screen. If you have some soldering skills, please solder the to pins to the respective ribbon that has come loose.
How do i know? Well.. I took my unit apart and accidently broke the connection of that same ribbon.. after that, only a black screen (no power to the LCD) Proceeded to clean and resolder the ribbon back and.. WORKS again!
I guess somehow it got disconnected when you took it apart to check the Board ID.. now that you have the solution and fimware.. please do the necessary! (i hope that you did not trash the unit yet)