I agree with Loly, the flash chip may well be damaged. But perhaps it is just flaky and will respond eventually so try again and again repeatedly to flash. What are the symptoms with this nuvi when turned on? Does it boot to the logo screen, show a bright white screen, faint light, etc. You can obviously reach pre-boot but what else can you tell us about it's history and what it's doing now? Did it brick after adding a map or other files or a fw upgrade, or for no apparent reason? Are you absolutely certain this unit is HWID is 0754 and not 0785 if it came to you bricked? In pre-boot, you can check the HWID with [Only registered and activated users can see links. ] if you haven't already confirmed it.