@seidenherb
That message at it's most benign and common occurrence means that the main 'system software' (firmware) contained in the device's region 14 is either missing, incomplete or corrupt. At it's worst it means the device has physical damage to the flash chip which cannot be remedied by software means. Let's proceed on the basis of it being the former, which is easily fixed by re-flashing the firmware in preboot mode. The device is not 'bricked' in the sense that it's unable to load necessary files on the boot sequence, as it's not able to use the firmware therefore no cure firmware needs to be loaded, just needs the original fw loaded in preboot. The device should have defaulted to preboot mode anyway if there is no flash chip fault and so you can proceed as follows behind the spoiler:
Spoiler: Click to Show
  • Open the attached ZIP file into a convenient directory (folder) on a Windows PC;
  • Drag the RGN file onto Updater.exe to open it;
  • Click the radio button next to "USB Device" on it's GUI;
  • Connect the eTrex to your PC, preferably using a desktop and a REAR USB2 port;
  • Watch the window adjacent to "USB Device" and when the device's detail appear in it click "OK";
  • Wait until Updater reports the flash has been succfessful before disconnecting from PC;
  • When the device is started it should boot normally.
NOTE: All flashing carries risk and it's all yours although it's minimal risk in this case. I'm assuming that you have a US/EU eTrex 10 with HWID 1304 and the flash kit uses that fw for the RGN file. If the device is An Asian or APEC model the flash won't be started because they have a different HWID.

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