Help me troubleshoot my MBP 17" that doesn't boot

I have a MacBook Pro 17" Mid-2010 that has been working fine until yesterday when it started booting to a blank, grey, screen. I have switched the optical drive for an MCE optibay with an SSD. The HDD is a 750GB seagate.

I have tried:
1. PRAM reset
2. SMC reset
3. start using the alt-key (I have one system on the ssd, one on the hdd, but the startup disk selector doesn't show.
4. safe mode
5. verbose mode
6. I took out the SSD as well as the HDD and put them in an external chassi. They booted fine on the other computer.
7. I tried cmd+r for lion recovery.
8. I tried booting from an external hdd that contains the lion disk image.
9. I tried using the supplied snow leopard disks in the optical drive (after i put it back.
10. apple hardware test disk

Nothing so far works. Just stuck at the grey screen.

I haven't started unscrewing it all yet but just removing the bottom lid all cables seem to be attached.

What else can I do? Any help would be greatly appreciated.

 

Did that (on USB-stick, HDD and DVD)

Logic board...****

 

Turns out the SSD was faulty somehow and hindered the boot. FYI.