Is there a way to lock this flash so that the up/down/left/right buttons temporarily don't change the power? I find that I often accidentally hit the down button with my forehead, and would like to stop messing up the exposure because of it!
I don't think there is a way in the flash of doing that, but as a DIY fix, how about putting some putty, or a sticky pad or something just below the 4 directional buttons, to help prevent stray head/hands/trees etc from hitting the buttons by accident.
Edit: Just as an example, I had an old remote some time ago where the button wasn't depressed into the moulded body, and it used to drain its battery in the camera bag. I cut an old credit card into a ring like a washer, that fitted round the button and just glued that on. If that's not high enough, you could cut two the same and stick them on top of each other