Hi Yes - it has a manual and TTL switch on the circuit board. Although mu understanding is that by using manual mode on the strobe itself it overrides it anyway. In my case the issue may have been strobe related but won;t be sure until I replace both strobes in the future. I am holding off until Inon decide if and when their new model will release and the retras have had more feedback! Best of luck
So when you mentioned on a dive that you had the problem and shutter release was locked up. Did you change your strobes back to manual during that dive? I just want to make sure that if TTL misbehaved, at least going back to manual would be a good back up. However, if the board decided to act up and there was no way to get around it while on a dive, may be it is not worth bothering with it, I guess.