There is a great guide to Debrand an AT&T Lumia 635 that I used and it worked great. However, there is no guide yet to Debrand the GoPhone Lumia 640. The guide for the 635 does not work on the 640. I have tried to flash other ROM's to the GoPhone 640 but AT&T has it locked down and no other ROM will flash. The AT&T 640 needs to be Debranded first. Any Guru's out there been successful?