I eventually got the update to take. From a clean install I tried the over the air update and the same problem occured - bricked device.

Heres some tips.

I used Ubuntu - if you don't have it available try getting a live cd and running the flasher from there. There is no reason the Windows flasher shouldn't work, but I trust Ubuntu a hell of a lot more than flashing a Linux device with Win7.

IT WILL NOT WORK ON A 64BIT OS - no idea why, but it won't.

Make sure you run flasher-3.6 -F etc without the phone connected via USB. You will get a prompt "no suitable device found, waiting.." at this stage, plug in via USB.

That should fix it, I'm relieved to know that I'm not the only one with this problem

Oh, and just for the record, I didn't have testing or devel enabled, and I don't really appreciate those people saying its user error, because I'm by no means an idiot.