A boot-looping device makes it hard to initiate a flash because it'll always drop out of preboot very quickly. Timing is crucial as is speed in initiating the flash. Most boot-looping devices will hold preboot when Updater.exe communicates with it but if it's got a failing flash chip the flash will inevitably fail even after initiation.

Use this method for best chance to catch the moment:
  • Load the cure RGN into Updater.exe;
  • Enable the radio button for "USB Device", position mouse cursor over "OK" button and leave the GUI open and visible on the PC's desktop;
  • Connect a 'Known Good' USB cable directly (no hub) to the PC's USB port (use only USB2 if available rather than USB3 and if using a desktop use rear rather than front port);
  • Ensure the device is fully OFF. Hold the power button down to force it off if necessay.
  • Hold the top LH corner of the nuvi's screen firmly (left thumb works best for me usually) and plug the USB cable into the device's socket with your right hand and quickly move it to the mouse while watching the window next to 'USB Device';
(This is where it gets interesting and you must move very quickly)
  • The instant you see the device information appear in the window next to 'USB Device' Click 'OK' button on the GUI and keep the firm steady pressure on the device screen

If you miss it start allover again. Persistence is key if this is a software bricking. If it catches the flash initially but keeps failing repeatedly with Updater's message 'unable to program memory region' it might be hardware failure and there's no software cure for that.