It seems that I’ve blown the flux capacitor (or some such) on my Holga’s flash. The most likely explanation is that the flash was overloaded at some point by a concentrated dose of awesomeness. I tried the ‘Max Breedon Technique™’ of fixing electronics [removing the case and poking the internals with a stick] to no avail.
Oh well, I’ll just have to grab another one off eBay for $25, at least I didn’t get one of those White Stripes ones that cost $180US. I’m also eyeing off the new Holga 135BC, which combines all the Holga’s quirks with the convenience of 35mm film.