2008 MacBook Core 2 Duo Internal Screen not recognized/Connected

I have picked up my sisters old Macbook Core 2 Duo 2008 - 2.1ghz, It works fine with External Screen but the Internal Screen will not turn on/detect? Has anybody ever experienced/repaired this?

Just for info, I have already:

1. Reset PRAM/NVRAM

2. Tried a working inverter and LVDS cable from a tested working macbook of the same age.

3. Changed the battery connector/sleep switch for a tested working one.

It boots fine and external monitor works perfect via Mini DVI.

Internal Screen is however Black, No back light and no image at all (tried torch technique too)

I cant think of what to try next, any help is appreciated.