With the other tools are the formats completing successfully? I wouldn't trust windows built-in tool even with 'Perform a quick format' box unchecked. Rufus is more reliable imo. If you followed the settings in the RMPrepUSB thread's initial post and it refuses to "find" the device's internal memory even after allowing it to be selected then it may be finding problems stopping it from proceeding.

You can try to flash newer firmware in preboot mode, if that fails then it's confirmed as flash damage taken in combination with it not properly saving files written to its file system.