No Backlight even with new LCD and inverter board + cable

I have so far replaced the LCD screen, inverter board, and inverter cable (individually) on my Early 2008 Penryn macbook 2.4ghz because my backlight keeps failing. I can still see the image dimly and external monitor display is fine.

The backlight will come on upon power up for a short time then go off, and for a short time doing the "brightness down then back up again" thing will work, and after that there's nothing I can do to get the light back on, not even restart.

After I replaced the LCD last night I used to computer solidly for around 3 hours but 4 or 5 times if I touched the screen or moved the laptop even the tiniest amount the backlight went off again. I closed it to go to sleep last night (not shut down) and this morning it is back to not coming on whatsoever.

So:

- clean the fan, logic board and apply thermal paste?

- Try ANOTHER inverter cable?

- Do what 'Rob Orr' suggests here:

www.ifixit.com/Answers/View/69120/No+backlight,+tried+inverter,+what+now

Thanks, I'm soooo frustrated!