dont know if its been posted or not but on the v12 when the sticker was on the back, it was possible to open without removing warranty sticker by opening like a book, sony must have realised this and moved the sticker to underneath covering one of the screws, when you remove the words void come through the sticker.
with a blade (box cutter) start at one end and slowly slide the blade underneath sticker, this will lift sticker keeping it intact, you only need to go far enough to remove screw cover and screw.
remove screw and put sticker back down, mod your pstwo,
when finished do the same to put screw back in and wipe over sticker to put back down flat.
hope this is of help to someone