If it is just downloading the flash from Nokia, it hasn't necessarily done anything to your phone yet. You should be able to disconnect the phone without any damage.
Damage only occurs if it NSU is actually dumping the flash on the phone.
I Just performed the E6 #2. I thought it was going to be an E6 #1 but I've had a ton of coffee this morning and for me it's like taking a laxative. Anyone else out there have any performances worth mentioning?