Non vivo?
You need a LOT of luck, prayer, voodoo magic, and assundry such items. The non-vivo ones were a VERY low probability of success. I believe that most of them were hard-locked against being opened, which means you get to try your soldering prowess on the four gold dots above the core.
I think a scant few of the non-vivo pro's were just bios locked, and could be reflashed. But those were very few and far between, if I remember correctly.