I have a Samsung Galaxy S3, which is locked to the Three network in the UK. I have a buyer who wants this and they've asked me to root and unlock the device to all networks using the 'cf-root' method. Can someone give me an easy guide to do this and let me know if there is anything I need to consider about using this method before posting the phone to the buyer? To my knowledge, the S3 is running an early version of Jelly Bean. Thanks.