A user by the name of longshot442 from XDA forum has published a 404MB file which contains the official RTM build of Mango, which is, the build 7720.
It has been claimed that users are able to flash devices ranging from NoDo, 7661 or build 7712 up to 7720. To do this, you do not need to restore from your backup, but instead can directly update.
User cyberdel among the first to successfully flash the phone with the once the file was leaked:
“install on htc trophy is finished:
at first i see on the bootscreen there is no mark anymore like “Not for resale” an Version is…. tada…. 7.10.7720.68
i am very happy now, good night”
Others have since reported success as well, regardless of device, carrier or network i.e. which tells us that the files might just be the developer release, meaning device neutral. Instructions, translated from German, can be found here. You can download the files at your risk from here or here. Original thread at XDA starts here, which we strongly encourage you to read first! Discuss in comments.
Remember, using this is at your own risk! The site do not endorse this method at all and take no responsibility when any issues occurred due to the flash. Having said that, enjoy.