@kopca
The second method is far more risky if the first method results were unsatisfactory. The second method, used successfully, will completely convert the nuvi 27x7 to dezl by remapping the region layout of the flash chip, loading new boot.bin (it's actually the ramloader) to a virtual region 12 which in turn flashes the physical regions 5 and 43 with dezl boot data. It also alters the HWID of the device. If the result is a bricked device which cannot boot at all then you may not be able to flash the original nuvi boot.bin back and re-convert to 2757. If you don't understand that or don't accept the risk of an unusable device then it's best not to attempt the full conversion imo.

Clear NV (non-volatile memory) basically resets the device completely so all user-entered data and more is deleted and the device in all practical respects is returned to factory settings. How to do it is [Only registered and activated users can see links. ].

Using anything other than the safe-naming convention of XXXX01000xxx.RGN (where XXXX is the device's present HWID and xxx is the firmware version) will force the flash in Updater.exe because there is no check made of Updater of the device's HWID before the flash is initiated. Using safe-naming the flash is rejected if the first 4 numerals don't match the device's HWID. Even if one zero is left out of the middle digits RGN's file name (i.e XXXX100xxx instead of XXXX01000xxx) that precaution is skipped. Using "OUT.RGN" is just a common custom to easily and quickly identify an RGN file intended to flash different firmware in a complete conversion attempt. Again, if you don't understand this don't do it.