IMPORTANT! If you want HELP in case of a bricked Garmin device, please follow this

**hiban** · 18th May 2021, 03:28 PM

Thank you so much for your reply.

Here's what I'm able to achieve so far:

1.- Turn off watch holding power button for more than 15 seconds.
2.- Press and hold UP button (this prevents the watch from rebooting when connected to PC, does not pass the garmin logo however).
3.- While holding up button, connect to PC.
4.- PC recognizes it as "Garmin USB GPS" since I have the drivers installed.

However, I cannot access its content via mass storage and neither Garmin Express or Webupdater dectect it. It seems by what the updater says that the current firmware the watch has is version 8.40 but I couldn't find it since garmin removed old firmwares from their web.

I can, however, "update" it with the updater. I dowloaded the 9.9 firmware of the watch, and I am able to do the update (while holding the Up button). The updater says everything went well, the watch stays for a little longer on the garmin logo but then bootloops again.

Spoiler: images

Again, thank you so much for your help.

**Cnfhbr** · 19th May 2021, 04:14 PM

@Andy Waltson

All your manipulations with the .gcd file of the Fenix 6S Pro firmware don't make sense, because this file is securely encrypted.

**Andy Waltson** · 20th May 2021, 04:50 PM

@Cnfhbr Clear, thank you. Is there any chance to upload original .gcd firmware in pre-boot state?

Edit:
@Cnfhbr Obvious question in this case - why Garmin's WebUpdater cannot flush .gcd encrypted by Garmin however device is detected by tool?
Same for Garmin Express. So manufacturer can deliver non-properly tested firmware and brick devices, but does not provide tools for recovery...

**Cnfhbr** · 20th May 2021, 07:00 PM

Originally Posted by Andy Waltson

So manufacturer can deliver non-properly tested firmware and brick devices, but does not provide tools for recovery...

Usually Garmin delivers 'non-properly tested firmware' with the possibility of a revert to the last public release software, for example:

Code:

Please Login or Register to see the links

In your case, you should contact Garmin's technical support, I guess.

**Andy Waltson** · 20th May 2021, 07:54 PM

Spoiler: pic 1

Those "instructions" does not make sense. If GARMIN folder would be available after deadly 16.60 firmware update I wouldn't bother people at forums and immediately reverted it back.
Also I've tried drag-and-drop of GUPDATE.GCD into WebUpdater from System_1630 folder. The same error:

Spoiler: pic 2

So GARMIN's tools cannot flash their own devices even if they are detected by OS ("GARMIN USB GPS"). But obviously there is a way to flash memory in that state (RGN Tool as example). Poor design decision from software engineering point of view.

In your case, you should contact Garmin's technical support, I guess.

I've already done that, no response at the moment...

Can only thank you to people responding here.

**hiban** · 22nd May 2021, 02:09 PM

@Butters

Thanks again. I read and tried to follow the instructions but I fail at the very first part. I can't get my HWID number on the watch via the G7towin tool.

Spoiler: images

Also, while trying to make a cure fw, I cannot even start because it asks for a gcd file and all the firmwares I was able to download from garmin and perry's web are already rgn files

When using the G7towin tool it somhows recognizes the watch connected because, if I do the proccess without the watch, it inmediatly pop ups the message. If I do it with the watch connected and in pre-boot mode, it takes a few seconds thinking but then fails.

I'm starting to think the watch is more than dead.

Thanks for all your help.

**ThatRinoGuy** · 6th February 2023, 05:05 AM

Hello--

I have a Rino 650 and 655t that I acquired second hand. They would freeze as they powered up displaying "updating waypoints and trackways". I used GarminCure3 to get access to USB mass storage. I installed FW 1247 and SW 5.10. Garmin Express crashes on my PC when I try to start it, but Garmin's other applications (BaseCamp, MapInstaller, etc) work to update software, and I can navigate the devices' memories via USB.

Now I can't get the devices out of USB. When I disconnect them and power them up, I get the Garmin logo and the USB symbol. The devices shut off shortly thereafter. I have deleted GUPDATE.GDC, but it looks like there's something else interfering with startup. I have other, functional devices to serve as templates, and don't see anything obviously interfering.

Thanks much for your thoughts.

Joe

**lixivia** · 17th August 2025, 12:10 PM

Hello, I have the same problem, my Garmin 6 stayed the same to make firmware changes... did you get to solve it? Thank you

**mariusgarmin** · 9th June 2026, 01:36 PM

Hi everyone,

My Garmin Forerunner 645 Music has been stuck in a boot loop (blue Garmin triangle logo repeating endlessly) for a few days, most likely caused by the TopoActive 2026.10 map update.

What I've already tried:

Power off/on → no effect
Master reset (holding UP) → no beep/vibration, doesn't work
WebUpdater with recovery mode (holding UP + START while plugging USB) → device is recognized, but update fails with "corrupted file" error
Garmin Express → doesn't recognize the device
Garmin support → told me the model is no longer covered
Diagnosis from Garmin Express logs:
The device connects in GarminMode but reports Unit ID = 0. The exact error from the log:
GET .../unitids/0?primaryFirmwarePartNumber=006-B2888-00 → 400 "Unit ID is required"
This explains why WebUpdater rejects the firmware — it can't validate the device identity.

Device info:

Model: Forerunner 645 Music
Firmware part number: 006-B2888-00
USB VID/PID: VID_091E / PID_0003
OS: Windows 11
What I can do:

Hold UP + START to stay in recovery/preboot mode (I can tape the buttons)
Device is detected by Updater.exe in this mode
Would anyone have the RGN firmware file for this model and the correct HWID, so I can attempt a forced flash via Updater.exe? Any guidance appreciated.

Thank you!

**Butters** · 24th May 2021, 11:39 AM

@Andy Waltson
Garmin seems to have posted those instructions to help users with V16.10 overcome the possible errors as listed in the Change History from 16.10 to 16.30. The instructions certainly are not intended to help a user 'unbrick' a device because clearly such a device doesn't have MSM access to drop a GCD file into the internal memory. In your case with V16.60 onboard it's not possible to unbrick it with conventional methods because as confirmed by Cnfhbr the firmware is encrypted and therefore defies any attempt to manipulate it in the usual fashions. I would think his (tentative/hesitant) advice to "contact Garmin's technical support, I guess" is the best we can do here unfortunately and he only gave those links as an example of Garmin's attempts to help users revert from a flaky, albeit working, fw rather than as serious help for bricked devices.

@hiban
RGN_Tool reports that Forerunner920XT_990.rgn is "an RGN within an RGN" and upon following this message's direction, i.e.:

Spoiler: small image

we find the HWID is 1765 after opening that saved fw_all.rgn in RGN_Tool:

Spoiler: image

This isn't a "usual" Garmin firmware in that there is no boot.bin and the entire fw consists of solely one section, the main (system) software, fw_all.bin, which is flashed to region 14 (hex 0E). The expected boot.bin which is normally contained in that first section, and is actually the ramloader, is missing so the fw flash must be initiated by some other means. I'm so sorry but i personally cannot think of anything further to try and i hope someone else has the knowledge to help you.