The mass storage device implementation is not complete but exploit the way Windows allocate blocks for a file. The real firmware always starts from sector 4 (512 byte sectors) and on OS X and Linux people have been using dd to just write the firmware to the physical device starting from sector 4 to program firmware. Apparently the anniversary update is checking integrity more stringently.
Over the last couple of days I have been tinkering with the Windows API to come up with a tool that directly access physical sectors of the drive. Basically we called CreateFile with path \\.\PhysicalDriveN to access the disk. Now here is the biggest problem: to gain sector-level access one must have administrator privileges. To us this is a huge major setback. We have a dedicated computer running a custom programming tool to write firmware on our production line but we don't want that computer to be always running as administrator. We used to be able to do USB firmware programming with only user-level access.
I think NXP could also fix the silicon, but this would not have helped with the stock we already have on our inventory.
