some people have a problem with checksum error while upgrading bootloader.
After this error ,you can flash wp7rom but windows will not start.
And you can go back to wm6.5
I had this problem too. Problem was solved by flashing all files: ENPRG8...
guys please can you define what you mean by a locked card ?
in some cases one partition is visible and therefore you can format it from windows(by using sdformater or other tools), but in other cases all card area is encrypted and windows can't...