Well, I got impatient a couple of days ago and decided to de-brand from Vodafone.
The product code changing with Nemisis was straight-forward enough - once I reverted back to an older version of the Nokia software which was on my laptop (The latest version of Nokia software wouldn't allow Nemesis to read the
N95's product code etc.)
Following the product code change I then went on to the firmware update (I was then back on the PC using the latest version of Nokia software). It showed that the
N95 was on 15... and the latest version was 20... I then went on to update the phone.
It got to what looked like around 75% of the way through and I then got a message saying something like "Disconnect the power and remove the battery, then reconnect"... you probably know, or can probably guess the rest.
The 'bricked'
N95 is now on it's way back to Nokia for repair.