I flashed the wrong firmware on naze32 rev6 controller, can I re-flashed (overwrite) w/correct firmware?
yes, you should be able to flash it with the latest Naze32 code available via the cleanflight/betaflight firmware flasher.
Hint: The password should be at least twelve characters long. To make it stronger, use upper and lower case letters, numbers, and symbols like ! " ? $ % ^ & ).