So i've concluded that rather just being a power supply - it's the actual miner. anyone know how to reset the bugger
I would start by looking at the backplane caps, and removing them if they look like they've failed.
If no help is to be had there, I would then remove all but one of the hashing modules from the backplane and see if it will start up like that. If so, reconnect another, etc, and see if you can isolate one of them that pisses it off.
Did just that. It worked. Found a dead module. Another module has 1 dead chip and 1 live chip. So I've asked BlackArrow to send out a few replacement boards and I'll just swap the heatsinks over. Let's see if they will do that. I'd contact MinerSource, but since they don't respond to emails, private messages and they cancelled their phone number, I'm not sure how to get a hold of them.
Update: while MS normally has not responded promptly, I got a response about the faulty hashboard and he said that they have replacements. So perhaps there is some light in all of this.