My Canon 550ex wouldn't switch on yesterday. Completely dead. Changed the batteries (twice). Still nothing, no indication of life. It was fine last time I used it about a week ago.
Is there anything that can be done?
Another solution I saw (can't find the original link anymore), was to take the batteries out and switch on and off again. Apparently this 'resets' the electronics.
I don't know if this actually works. I'm just adding it here as something to try for people who search this question.
After trying as few things and playing around with the flash with no success, I found the following thread on the web.
The advice given is :
I actually works! To rub the terminals inside the battery compartment I wrapped a thin, slightly damp rag around the eraser end of a pencil and gave it a few spins. The terminals didn't look corroded or damaged. Afterwards the speedlite switched on, good as new.