Macbook Pro 13 won't turn on

I've got a Macbook Pro 13 2.26 GHz model A1278. I bought this machine used but it has worked fine since Feb. (It is however out of warranty) The other night it slid off the bed on to the floor (lush carpet) - I picked it up, seemed fine and I continued to use it (watching Netflix), when I shut the lid it did not sleep but instead shut off.
When I tried to turn it back on, the power/sleep light flashed once and I heard a click, but it did not power up. The next morning I tried turning it on again and it powered up normally, however, when I shut the lid, it lost power and when I tried to turn it back on same thing - one flash of the light and a click.
The click appears to be coming from somewhere near the power button (inside case) possibly the superdrive.
I have repaired many different macbook pros with pretty good success, so I took it completely apart - removed, battery, hard drive, super drive, logic board, even removed the screen looking for some kind of damage from the fall - found none.
I reassembled, and it started up normally (except clock was reset). When I was done, I shut down and then it was back to one flash of the light and a click when trying to turn on. I have dissembled and reassembled a few times now and always the same thing - I get one good boot where everything works fine, but after shutting down (or if I sleep, it shuts down too), I'm back to the 1 flash of the light and the click when trying to boot back up.
Any one have any ideas or suggestions?

Did you try resetting the SMC? Also do a PRAM-NVRAM reset while you're at it.

It sounds like the System Management Controller has gotten brain damage. It sometimes happens after a drop, bang, thunk, or what have you.... The SMC reset may get it going right again.

I did reset the SMC. However it is not booting at all now even after disassembly, so I can't reset the PRAM.
Now I get the light flash and click every time. The click is right by the LED and HD. If I disconnect the HD, I don't get the click or the light flash. I tried with a HD that works in another machine. Maybe the disk controller went bad?
Also, after pressing the power button, the fan spins for a second or two and then stops.

Any further suggestions would be appreciated.

It's back to where it will boot if it sits long enough. With no hard drive it boots to the gray screen most of the time.
Don't feel like it will ever be that reliable, so I'm putting it on ebay as needs repair.

It sounds like the hard drive may have been damaged in the fall if it will boot OK from the startup disk with the drive removed. Did you try removing the drive connector cable from the logic board and reseating it? You may just have a loose cable. Also try reseating the memory modules.