Rear seat entertainment system

[hazee]

I have bought a used X5 2009 model with below attached entertainment system installed.

I have found the part number (65 12 0 421 339) but can not figure out what is faulty? I have got no idea how to open the screens from the seats or find the wiring path to find the issue or may be resolve it. I have also found the below

http://bmwfans.info/parts/catalog/E7..._dvd_advanced/

How to troubleshoot this or which part to be replaced. I even prefer to remove the system and install a new one if this one cant be repaired.

Refer to attached pics.

Thanks in advance.