Macbook Pro 17" Unibody. No Startup chime, no display, sleep indicator solid white.

My MacBook Pro Unibody 17" (Mid 2010) has suddenly stopped working.

There is no startup chime, no display and the sleep indicator light stays on solid white.

Fans power up, as does HDD. Battery charges as normal (indicator on charger and charge level indicator both react normally), and ALS is working (Sleep indicator dims when camera is covered).

Identical issues to this: http://support.apple.com/kb/TS4088 and this: http://support.apple.com/kb/TS2377

However the 17" Model is not supposed to be affected by this (in spite of both the mid 2010 15" and 17" models carrying the GeForce 330m).

I have removed and reseated the RAM, HDD, Super Drive, Camera and Bluetooth/Wifi cables (all the easily accessible cables) to no avail.

Have recently installed a Samsung SSD and Mountain Lion, but both were working well for several weeks prior to this with no instability or noticable crashes.

Any help or suggestions would be gratly appreciated.

Luke