I took my knapsack out of my car today completely forgetting the bottom was unzipped and flung it over my shoulder, then I heard the sound of something hitting the asphalt, my SB600. It powers on and the display works, it was flashing when I pressed the FLASH button, but now it wont. I have mounted it on two different bodies and it does not flash in any mode. Guess it has to go in for an estimate. Any ideas?